In July 2000 this male house finch with seriously messed up eyes began showing up at my window feeder. I checked on the web to see what I could learn about the condition, and whether there was anything I could or should do for the bird. The disease, it turns out, is called Mycoplasma Gallisepticum, and a birder named Jim Cook has a truly excellent site dedicated to explaining what it is, where it came from, and what can be done about it. Check it out if you care about birds or have seen birds with this condition in your area.
I contacted the local wildlife rescue center here in Lake County to see if they would be able to treat the bird should I be able to catch him. They're of the school that the illness is better left to the bird's immune system to shake off and advised against my trying to capture it. He showed up at the window regularly for about two weeks, then disappeared and hasn't been seen since.
Jim Cook's House Finch Conjuctivitis page: http://members.aol.com/FinchMG/Index.htm