I like the idea of games with codified (if not coded) Influence action systems. You get a regular allowance of action points based on some stats and time or whatever. The ability to hand out more is cool, especially if they can be scoped to the domain of the plot (Underworld, Occult, Law, etc). Your actions can then be to use that influence to get a gun or a bag of money or a jar of newt blood or a speeding ticket waived later. Perhaps picking up the gun and getting rid of it earns you a favor represented as influence.
As for tangible things, giving people things they could reasonably get on their own seems sensible out of the gate. What supers don't really have a means of either breaking into a house/store/whatever and stealing a gun or "talking" someone out of the gun they have? A Ma Deuce? No. A Beretta? Sure, why not? A grand claive? Keep dreaming.
On CoH I created an object that would give whoever carried it a small stat bonus. Being ICly cursed (unbeknownst to the characters) it would randomly @pemit crazy things to the player only or to the others in the room only.
A good reward is itself a plot vehicle.
