Personally I always thought it would be cool to create some kind of peer-xp system that relies on players basically saying, Yo, this guy is pretty awesome, you should check him out. They've done this to an extent with the who's your favorite character or asking who deserves whatever on FB, but I'd rather see something coded along these lines:
Character X is pretty awesome, and gets IMMxp on a regular basis (lolz). Because IMMs feel Character X is deserving/has good judgment, allow him/her to xpadd mortals with something small (100-200?) and leave comments/flags for IMMs that nudge them to maybe watch this guy because he's flying under the radar and is pretty cool from a RP standpoint. Maybe they get a weekly report displaying who these characters are both as a monitoring system for abuse/reward, or at least get a ping about what characters are garnering generally positive reviews. Something like this would have a HUGE timer (and lot of red tape), but might help with people who a) don't want to interact (or maybe don't have a RP reason) with IMMs, b) play odd hours, c) encourage/give incentive for people to RP/interact with each other and not just "turn it on" for IMMs.
Characters getting this sort of ability might be based on IMMxp to start, but you could always turn it into a pyramid scheme where if people accrue enough peer-approved xp, they'd earn the right (or at least a review) to do it for others.
Might be a lot of room for abuse in the system, but I think it could be a viable alternative to IMMxp whoring.