Well, I did some cleaning on the rear derailleur this evening, it shined up really well and seems to be working properly. I did end up taking it completely apart and had a little difficulty puting it back together again because of the spring tension (and my general awkwardness, I guess). But it looks great and I'll definitely be re-installing it. Thanks again for all of the advise. Tomorrow, the front derailleur! And I'll get those scans up as soon as I can.