This site has very in-depth information about how to perform exercises and what muscles they work. you have to look around to find some but it is interesting.
http://exrx.net/index.html
I just like this one.
http://exrx.net/Lists/PowerExercises.html
http://exrx.net/Lists/Directory.html
this one has training programs on the right side.
http://exrx.net/Exercise.html