Any ideas how to make this deck faster?

Creatures:
x2 Phyrexian Ghoul
x2 Crypt Keeper
x2 Zombie Cannibal
x2 Boneknitter
x1 Festering Goblin
x4 Nantuko Husk
x4 Shepherd of Rot
x4 Gempalm Polluter
x4 Skinthinner
x3 Withered Wretch
x4 Carrion Feeder
x2 Undead Warchief
x4 Vengeful Dead

Enchantments:
x1 Cover of Darkness

Lands:
x20 Swamp
x1 Unholy Grotto

just a few questions:

is this primarily for casual play? or are you looking to speed it up enough to play in a tournament of some kind (followup: if it's a casual game, what sort of decks do you usually play against?)

should rares be included in the suggestions? or should I stick to commons and uncommons?

what range of sets do you want me to restrict suggestions to?

for some information, I've been playing amateur level magic since tempest, and I am currently pursuing certification as a level I judge.

The tournament I play in is Type 1 (no Power Nine). Cards should be restricted to mainly uncommons, but a few of the newer rares may be fine.

I'm looking mainly for cheap zombies, don't have to have effects, but they can. Would like something like a Zombie Overrun deck.

I'm not terribly familiar with the state of the graveyard in Type I, do you find really needing this much graveyard-hate? (2x crypt creeper + 2x zombie cannibal + 3x withered wretch is alot of hate) I've found 4x withered to be enough even in Odyssey/Onslaught Type II, which is very graveyard heavy.

my recommendations for speeding the deck up are to include as many copies of Twisted abomination as you can (Scourge - common) it's a 'landcycler' that will cycle off for an extra swamp in the early game, or come down for a 5/3 regenerator(B) for 5B in the late. also a great target for recursion, if you include it.
it's a very useful card for making sure you don't miss any of those land drops.

as far as creatures in the 1 mana cost range... I have generally found both festering goblin (onslaught - common) and maggot carrier (planeshift - common) to be more effective than the zombie cannibal.

overall, the mana curve isn't so bad, most of your creatures are in the 1 to 3 mana range, with a few heavy hitters in the upper range, and nothing over 6 (of which they cycle anyway) so I'd guess one of the slowdowns is a small hand size in the mid-late game.

one possible solution to fix this would be to consider swapping in a few copies of corpse harvester (legions - uncommon) for either ghouls or skinthinners.
Corpse harvester sacrifices a creature in exchange for searching a swamp and a zombie out of your library.

which brings me to my next point: 5 mana for targeted removal is steep in casual/type I. realizing that enchantments are ripe for removal, the best kind of removal is recurrable. Call to the Grave (rare - scourge) would work excellently for this deck, as none of your creatures are Non-zombies. if you would rather have an activated (as opposed to triggered) ability, Attrition (rare - Urza's Saga) is also an excellent choice. (I realize this card is probably difficult to get right now)
other possibilities include the Grave Pact (rare - 8th/Stronghold) Deathmatch (rare - Onslaught) combo, or a good old pestilence or three (you can do worse than to pack one of those into every deck you own) you have enough pumping creatures that you could keep several of your creatures intact in the first main, and attack into the empty redzone post pestilence.

if you're looking for a creature-related solution, deathmark Prelate (I'm aware, it's not a zombie --- uncommon - legions) is a decent solution.

Also, the deck's threat against non-black decks can be increased by running additional copies of Cover of darkness, if you have them. this again would probably be dependent on the percentage of non-black decks you field against, and what your expectations are for actual damage dealing.

on the land front, good acceleration in a mono-black deck can be gotten by running 1-3 (2 is usually a good number) of cabal coffers (torment - uncommon)
a dead land before you get three swamps in play, it gets sick once you drop your seventh or eighth land, allowing you to power out entire hands of creatures.

another thing to look into would be (cheap) recursion, because there is a significant quantity of sacrifice going on in this deck, recursion would be a good way to keep threats on the board, some of my favorites include oversold cemetery (onslaught - rare) Lord of the Undead (planeshift - rare added bonus: another +1/+1 to all zombies) and disturbed burial (tempest - common) but there's many options, so I would encourage you to look around for what you feel fits the deck the best. Added bonus: recursion to hand / top of library gives your Gempalms extra utility!

so a general outline for your deck would run something like this.

4x Carrion Feeder
4x another 1drop zombie (probably festering goblin, but there's several others)
4x Nantuko husk
4x sheperd of rot
4x Gempalm polluter
4x Twisted abomination
4x vengeful dead
3x withered wretch
2x Undead Chieftan
1-5x recursion creatures/abilities
2-5x removal creatures/abilities (I prefer enchantments)
0-3x another 1drop zombie (esp. if you have powerful comes into play effects, or need cheap sacrifices.
0-2x Phyrexian ghoul (only if you think you really need 'extra' nantuko husks)
0-2x corpse harvester (I'd probably only run one)
around 21 total lands +/- based on tooling.

also, don't be afraid to run a few cards over 60 if you add more lands.

in general, the only thing over four mana you'll be casting is going to be the undead chieftan, and possibly the corpse harvester. most of the other high cost creatures will be cycled anyway.

by no means a thorough list, this should at least point you in the right direction.

note: if pure speed is your primary concern, you could do worse than to pack a few graveborn muses (legions - rare) as your only over 3 cost zombie, and just stuff it as full of 1-3 cost zombies as you can. combined with heavy recursion, and or cover of darkness, it would be possible to overrun the opposition.

easy sacrifice and decent recursion are a must though, if you don't want to wipe yourself out with the muse.

[edit] it occured to me after posting that I overlooked one of the important zombies in scourge: putrid raptor (scourge - uncommon) it's basically a hidden horror with zombie as it's creature type. if you're looking for a good solid 3-drop, putrid raptor is definitely up there in a zombie heavy deck. [/edit]

My Zombie Cleric deck:

4 X Rotlung Reanimator
4 X Shepherd of Rot
4 X Boneknitter
4 X Withered Wretch
4 X Fallen Cleric
4 X Soulless One
4 X Gempalm Polluter
4 X Vile Deacon
4 X Cruel Revival
4 X Starlit Sanctum
20 X Swamp

You get the best of both worlds. Zombies and Clerics. The clincher is with the Starlit Sanctums. They make Vile Deacon sacs deadly. This deck is also Onslaught Block legal.

I'm thinking of a new purely Artifact deck, goes something like this:

Creatures:
x4 Frogmite
x4 Lodestone Myr
x4 Myr Enforcer
x4 Myr Retriever
x4 Ornithopter

Artifacts:
x2 Gate to the AEther
x4 Scale of Chiss-Goria
x3 Talisman of Dominance
x3 Talisman of Progress
x4 Tooth of Chiss-Goria
x4 Welding Jar

Land:
x4 Ancient Den
x4 Seat of the Synod
x4 Vault of Whispers
x4 Great Furnace
x4 Tree of Tales

The main idea will be to pump the Lodestones and to get out creatures quickly.

Ideal first hand:
x1 Land
x1 Ornithopter
x1 Scale of Chiss-Goria
x1 Tooth of Chiss-Goria
x1 Frogmite
x1 Welding Jar
x1 Myr Enforcer

Play Land, play Ornithopter, play Welding Jar, play Scale, play Tooth, play Frogmite, tap Land, play Enforcer

Obviously, there are two huge weaknesses.

1) All Artifacts. Easily killed with things like Shatter.
2) Play a lot of stuff fast, leaving nothing in hand for backup.

I'm thinking about splashing some blue cards in to help counter, but I need ideas of what to take out first. Also other blue cards to aid in drawing, and possibly Mind's Eye to aid in more drawing.

Suggestions? Ideas? Feel free.

It's really too early to make any accurate predictions about the MBC (mirrodin block constructed) metagame, esp. concerning all artifact decks.

as a warning though, red/black can build a very aggressive removal deck... preliminary tests with my current version have convinced me the archetype is viable, but I have no definite build. (my version is rareless, but that may change as I get a better handle on the current environment)

it runs more or less like this:
creatures:
4xSlith Bloodletter
4xSlith Firewalker
4xFrogmite
3xSpikeshot Goblin
artifacts:
4xIsochron Scepter
2xFireshrieker
2xLoxodon warhammer
2xBanshee's blade
1xMask of memory
spells:
4x electrostatic bolt
4x shatter
2x shrapnel blast
Lands(26):
7x Swamp
7x Mountain
4x cloudpost
4x Great Furnace
4x Vault of Whispers

62 total cards::no sideboard (as of yet)

oh. and all the spells are targets for the 'scepter's imprint.
and a repeatable shrapnel blast can be very very messy.
and a repeatable shatter/electrostatic bolt takes most decks apart.

(tanka):
this (red/black) is shaping up to be the removal deck. (granted, probably much differently than mine) and Red/Green looks like it's going to be the artifact destruction deck for the metagame. if you can consistently outrace/outplay decks of both archetypes, you might have something with an all artifact deck.

my recommendation would be to definitely add some counterspelling to the deck. and additional card draw will also let you take full advantage of affinity. just remember that there aren't any ability counters in MBC, so if someone resolves a good 'scepter, it's going to be all over.

Cards I'm thinking of adding:

Annul*
Assert Authority*
Fabricate*
Inertia Bubble (Sideboard for the Isochroners)
Override*
Regress
Temporal Cascade (Out of cards? Do this and you get seven more options! )
Thirst for Knowledge
Thoughtcast*
Vedalken Archmage*

The ones that are asterixed are the ones that are hugely looking like going in. A few good counters and a couple of good drawers.

AEther Spellbomb
Chromatic Sphere (just for the draw ability, and to possibly filter stuff from Talismans so you don't take damage)
Chrome Mox (if I do throw in the blue cards)
Farsight Mask
Liar's Pendulum (for some fun)
Mind's Eye (grab a card each time the opponent does)
Mindstorm Crown (considering how fast this should be)
Tower of Fortune
Wizard Replica

All of these would do well to keep the deck going fast, but, at the same time, breaks the flow of the deck. I could use the Wiz Reps for countering (as they aid the Affinity) and things to help drawing. Probably would put out stuff for more countering and drawing to make the thing really fast. I'd like to keep it at 60-65 cards, though. 70 only if it has to be that big (everything depending on each other, for instance).