1) Pilot:
Pages 213 and 214 of the Shadowrun 4th Edition Core Rulebook give us some interesting (and I believe, often overlooked) rules for Pilot programs. The Pilot program is equal to and stands in for the System attribute for vehicles, drones, and agents, and also whichever mental attributes the vehicle/drone/agent may require. It also stands in for the Computer, Cybercombat, Data Search, and Hacking skills, as needed. Remember those for later.
The downside to a Pilot rating is that it intentionally made stupid. The Issuing Commands sidebar on page 214 of SR4; the Pilot Capabilities section of Arsenal on page 102; and in Unwired, the Scripting sidebar page 69, Agent Scripts page 100, To Mook Or Not To Mook sidebar page 101, and the Agent Competency sidebar page 111, all seem specifically designed to make Pilots and Agents retarded. The important part of all of this is the following - in nearly every instance, if something comes up that the Pilot is not "designed" for, you are supposed to roll a Pilot + Response Test to see if the Pilot can adapt. The Adaptability Autosoft (for either Pilots or Drones) can help with this limitation. This will also be important for later.
I would also like to point out that the Unrestricted Agent modifier from page 100 of Unwired is, in my opinion, largely unneeded. The same modification can be done with a simple Extended Test (To Mook Or Not To Mook sidebar, page 101), and it only applies to Agents - not Pilot programs for vehicles and drones (but only on a technicality).
2) Drones and Modifications:
Here's where it starts getting fun. There's certainly a limitation to the modifications we can put into drones to make them viable, but I've found something that helps significantly.
There's a modification for minidrones called "Limited Maneuverability" that adds 4 modification slots, and states that "A drone with limited maneuverability does not move on its own..." (Arsenal, page 139). This is important because it does not remove any speeds from the drone, it just states the drone cannot move on its own. A simple trick for getting more modification slots is by taking a minidrone, applying Limited Maneuverability, and then tacking on Walker Mode, Lighter Than Air, or Tracked Vehicle upgrades to get our movement option back while retaining many modification slots gained from Limited Maneuverability. Any loss of speed can be offset by the Turbocharger and Custom Engine, or you can just find other uses for them, such as the one I'm leading up to.
3) Software:
Now a Pilot program counts as a System, so we don't have to worry about that, but we still have to supply a Firewall. We also have some work to do to make the Pilot as flexible as possible.
Let's take a look at Software Suites from page 128 in Unwired first. This section tells us we can lump any software into one master program that runs like a single program, but has the functions of all the component parts. Note how it does not make any distinction or preference for what types of programs are allowed to be Suite'd together.
Let's also take a look at Software Bundles, page 127, Unwired. This is a "group discount" for buying multiple pre-packaged programs that gives a 10-20% discount overall.
Which leads us to the following: the best possible Software Suites nuyen can buy.
[ Spoiler ]
The only program I couldn't fit into a themed Suite was Command, which gets to sit all by itself taking up a processor limit for 600 nuyen or finishing up your Ergonomic payload (assuming a 6 Response/Pilot) for an extra 300.
Now a very important note that I hit just above is that Software Suites do not care what kind of software they Suite - they just lump it together, which leads us to:
[ Spoiler ]
Now what would make this whole thing even better would be to toss that Command program that we couldn't place earlier into that Basic Program.
That Adaptability Autosoft, when applied to a drone or Agent, allows the Pilot program to start functioning autonomously considerably easier, and a Pilot that can think for itself should also be able to select the programs/autosofts that are the most appropriate for a situation.
4) Theorhetical Application of Above:
Let's start putting all these puzzle pieces together now.
Let's do a warm-up easy drone/program combination: the Drone Soldier.
[ Spoiler ]
It should be noted that I am ignoring the Renraku's "senior citizen syndrome" - the inability to kick, punch, defend itself, ect. I have this setup saved to my files as a PR-3 encounter as-is. We can also easily upgrade the Pilot rating for the Manservant and toss in an Adaptability autosoft (and possibly a Fuzzy Logic system) to make a squad leader, or easily swap out weapons and Targetting autosofts to make different strike teams. Using an Ares Crusader, Ares Predator-III, a Remington 990, an Ares Alpha, or a Fichetti Pain Inducer are all valid and equally dangerous setups.
The plausibility of such a drone in any quasi-corporate setting is this: it is much cheaper to outfit or replace one of these drones than it is to train a metahuman for the same job. It also does not require pay, only upkeep, and there are no medical costs if it becomes damaged - just a repair bill.
Now let's try something a little more advanced: Glitch.
[ Spoiler ]
The sensors I've left blank so you can fill them yourself and tailor them to your own playstyle, although I'd highly suggest getting a tricked out microphone, a tricked out camera, and a R4 Ultrawideband Radar.
This drone is capable of hacking on its own, and with a R3 Adaptability autosoft has 15-18 dice to function autonomously, it'll be able to follow your commands and hack for you, as well as load and unload its autosofts/programs as the situation requires. With a skill of 6 in four of the five major hacking skills, and using some of the Software Suites from above, you're looking at a personal hacking device that rivals the most trained professionals the Sixth World has seen. If you add a R4 Electronic Warfare autosoft, Glitch will also be able to jam (assuming he has access to a jammer), intercept signals, and decrypt things as well.
In my personal opinion, Glitch is a worthy (though expensive) alternative to your everyday commlink. Vehicles and drones are allowed to do whatever they like, just like a normal matrix user, and with the high level of autonomy available with such little effort (but large bank account) they can replace the group's hacker (or at least give him a huge helping hand). The possibilities are extremely varied, and are basically only limited by your imagination (and again, your character's cash).
Nearly every character should be able to afford at least a basic drone. For example, a Renraku Manservant-III (man I love those things) with Fuzzy Logic and one Turbocharger, an Adaptability autosoft, and a handfull of other 'softs to your liking has a huge amount of versatile potential. He can be a mechanic/armorer, taking care of your items back at your base of operations (using the Mechanic/Armorer autosofts); he can be your driver, taking you wherever you want to go (after he loads the proper Maneuver Autosofts); and he could also be an additional gun on the battlefield (with Clearsight, Defense, and Targetting 'softs). And all of that is available for barely over 10,000 nuyen - cheap change in chargen and not that much on the streets.
AI PCs should also look at some of these builds for ideas. Renraku Manservants are really solid choices for a body out and about - they are extremely cheap, and their "-" availability means they are ubiquitous, two things important to 'runners. The Bust-a-Move is a cheaper drone and is much more overlooked alternative. An LEBD-1 can provide air support for a team, but brings more attention to the events (it's a restricted police drone - use at your own risk). The MCT Nissan and C-D Dalmatian are also good alternatives for air support, and they're not exactly expensive and have the benefit of being street legal.
I'll leave you guys with this one thought: the idea of a stock cyclopse monocycle hacking someone's commlink. As long as you upload the proper programs and the Pilot gets enough hits on its Rating + Response, it is absolutely possible. I bet you'll never look at a car the same way again.
End
So have I missed some things, or are the above more or less true? Discuss.
EDIT: Edited for compliance to rules for stock modifications.
EDIT #2: Updated for increased cost of autosofts, as per SR4A.