It would be very nice if there were some kind of way to get rid of bad or good reputation given to someone within a certain time constraint (perhaps 12 hrs) - in a sort of similar way to eBay's mutual retraction system with posting comments about a particular bidder. This way it makes it possible to get rid of points that were wrongly given out for either bad or good.
I definately think that we should be able to see who has given us reputation. It would, as YT said, stop clutter on the forums to a certain extent (although it won't eliminate it completely). It also complements my idea above to a certain extent.