What's the slickest, smartest thing a mage has done with magic that worked really well with a low Magic attribute?

Moved a small amount of rock to cause a very big avalanche. Done with a spell, but a small spirit could have also done it.

Generalization: Don't attack the thing that can resist your magic. Make something attack it that it cannot resist.

I had a group that would turn into birds and screw with the opposing forces in all manner of ways. Sometimes they'd enhance their strength with magic as well, leading to embarassing moments were guards got their asses handed to them by pigeons etc.

Good points. If you don't have the Magic to sling high-damaging spells against the opposition, try moving the plascrete from under their feet. Dig them an instant hole to drop into, then seal the top off.

I've always wanted to do an Avatar-inspired Bender...

My Last Magician utilized a lot of environmental manipulation spells, including a collection of Shape [Element] Spells that he thoroughly enjoyed.

Counterspelling.

My current druid has got Shape[Element] for Earth, Metal and Stone. Good fun. Magic is now 5 after 380 karma, so no longer low, but these work even if there is uncompensated BC.

Interesting Thread, this is one of the questions I'm pondering at this time as well.
So far, I have not found actual damage dealing spells, but a whole lot of utility spells...

So:
Detection spells:
"Mindlink": One hit and you link up with someone else. It's a communication path that can hardly be jammed.
"Detect Truth": A detection spell that works on you and with one hit will let you analyse whether or not someone is lying. - Turns out I was wrong about this one. Active detection spells can be resisted by anybody they're trying to detect, so in this case the liar gets a roll against the spell.
"Enhance Aim": It reduces the range categories for a shooting test by one per hit.
"Combat Sense" (detection) and "Deflection" (manipulation) will increase your pool for dodging bullets. In my opinion, every single die gained there is nice.

Health spells:
"Awaken": Will wake a sleeping or unconscious targets. Beats carrying chummers who took too many shocker rounds. Keep in mind that for unconscious people the threshold will not be 1, but rather their wound modifier.
"Nutrition", health spell, will keep you alive, the taste will just be rather bland.

Manipulation spells:
"Shapechange": A very nice spell. Sure, more hits will raise the animal form's attributes, but changing the shape is the main part. (already mentioned above)
"Sling": Nice to get stuff thrown into the right direction if you don't have the skill for that. Of course, damage and number of net hits are going to be low, so thrown weaponry is ineffective. You can throw anything with it, not just weapons designed for that. I imagine shocker bolts for crossbows will do nicely. Grenades come with their own damage code, as do monofilament bolas, if you want to get ugly...
"Mana Static": Creates a background count rating of hits. While more effective with more successes, a rating one or two BC can mess up low-rating foci, soften up spirits to gunfire, blind ghouls... or rob someone (say, a toxic shaman) of his or her astral domain if it is sufficiently low. If not, run.
"[Element] Aura": It will provide an elemental effect to any melee attacks the target makes and increase melee damage by number of hits. This will cancel "Immunity to Normal Weapons" for spirits and "Regeneration" for vampires and others. It usually halves armor - the element "Sound" will negate any armor.

A spirit of man with low force rating can still provide the power "Guard", which will make you immune to the nasty effects of glitches. Doubles well with skillwires and/or a low edge attribute, by the way.

With a low magic attribute, you really need to watch out for any background count. It'll break your spells and turn you mundane.

You know with all this talk of clever uses of magic, how do you guys usually handle Mindprobe aka "Interregation I win button"?

This is the great debate on most of the mentalist type spells.

While the target knows they are being probed, it does not necessarily tell them who is doing it to them.
Plus in regards to lawful usage, information gathered this way is generally not admissible in court, but that doesn't really matter to us neh?

So you could operate from a room full of people or as simple as throwing a bag over the guys head, probe them and laes them up before cutting them loose.

Of course this cuts both ways, so many tables usually have some self imposed restrictions on its usage, like reserving it only for the really desperate situations, so that the GM does not respond in kind by having local street gangers mindprobe you for blackmail material.

1 way is not allow the spell and another way is to have reprocutions later on.
I always think of mind probe as brain-rape and then a hatred may begin.

Well, I will only speak from a SR3 perspective here: One of the things that struck me odd with detection spells in general and Mind Probe in particular was the fact that the spells supposedly created a new sense (directional or omni-directional) but - unlike other sensory tests - usually determined their success rate based solely on the caster's initial casting successes instead of that created sense whenever the sense was used.

So my personal solution for Mind Probe was: First of all the caster had to maintain line of sight (as the created sense is directional) and instead of directly consulting the Mind Probe table after the spell was (successfully) cast I used the caster's net successes as the value for a virtual Intelligence attribute used for that particular sense and rolled that number of dice against TN of 4 + applicable modifiers in order to get the "actual" number of successes on the Mind Probe table. Additionally each individual memory of interest that the player was after demanded a separate such roll. Repeated searches for the same memory caused a +2 modifier. Just randomly searching the victim's mind for potentially interesting information also induced a modifier (IIRC I used +2 again) due to the victim getting lost in all his available memories without the "guidance" of the intruding magician.

No successes on such a test didn't mean that the player didn't get any information: The victim then temporarily got the upper hand and presented false memories but the player was aware of the falsehood. A complete failure (all 1s) got the player false memories and he believed them to be true.

Depending on the desired drama I also introduced a base time of 10 combat turns per probe action and only successes not spent on quality of information could be used to lower that time frame.

This limited actions like "I cast this to get incriminating info" against random targets and created a certain amount of randomness in the gained information (as well as taking some time to actually get it) and no more instant "I win this interrogation". Worked pretty well but had the drawback of increased number of dice rolls.

As far as "clever" use of magic (regardless of low and high magic ratings) is concerned: I always found it clever when a mage used his spells in a manner that didn't instantly scream "now there be use of magic". Like that mage who had a (limited) Shape [Concrete] spell he used to temporarily form caltrops and marbles to slow down pursuers or flatten vehicle tires with those caltrops instead of going ballistic with mana balls or power bolt.

If it's not Mindprobe, it would be Gamma-Scopalamine and/or some clever use of a transducer/DNI (that can read surface thoughts). And if it's not this, it's hacking the target's commlink to learn more or less everything he knows.
For me, it's a given: once the runners got their hands on someone, they can get all that this person knows. Mindprobe is just a way to skip/speed up interrogation.

The trick is to design runs where people take that into account. Maybe most people involved only know a part of the whole plan, maybe the most obvious targets of such attempts have been fed with wrong information or one "honey pot" or "canary" information (an intel that is used to trigger an alert when compromised) or the whole thing is planned to be resilient to information breaches.

Exactly. There's a reason why the military has a "counter-intelligence" office.

If you can count on a lot of hits, there's no reason to have your mind-probe target conscious while you do it.
Stun bolt then mind probe is the best way to get information.
Or mind probe followed by alter memory, but that's not as good.

For the OP, a low powered magic fingers can do a million and one useful things. It's my favorite spell for anyone who's only got a little magic.
Also, a force 1 spirit can still materialize inside a room and open the door for you.

Oh yes, because the supercriminals for hire (aka shadowrunners) are loved by everyone everywhere. Especially by the people they shot and/or tased.

Get a reputation for Mind-Raping people, and even other Shadowrunners will start to avoid you.

Yup. My group looked at me really differently after I tossed 24 dice for a Compulsion during an interrogation.

By simply never getting enough net hits to read more than surface thoughts.

Surface thoughts is an interesting thing though... You can direct questions to the target which will force things to the surface, even if to actively avoid/not answer said question. There is a perfect example of this in Babylon 5.

YES. I believe it was somewhere around Season 2 and it was Talia Winters helping with a commercial deal (ostensibly).