Hmm...it appears there may already be an application of this sort on facebook...I'm going to explore this a little bit and see how their app works because their description sounds very similar to what I was thinking of doing, and I might just help their development team.
Still, let me know if you guys are interested in working on another one anyway...
Here is the link to "gasbook" for facebook
http://www.facebook.com/apps/applica...34645610&ref=s