Mars craters
Though the relative merits of wet Mars research and Mars cratering work are debatable, I think the cratering studies do have a considerable degree of importance, regarding future Earth-threatening bodies and for many other reasons.
It seems that the volunteer "clickworkers" program is on a frayed shoestring budget, but I think efforts like this could have worthwhile benefits, and could do a lot more with just a little cash.
http://clickworkers.arc.nasa.gov/
Take a look, it gets kind of addictive - or is that just me?