Cool reference! This is going into the anatomy portion of the FAQ...
This is just a site I found of a guy's head with a whole bunch of facial expressions shown. They don'e have the name or type of expression underneath most of them, but you can guess what expression he's doing based on that info.
This is kind of a joke site by a guy who has nothing better to do than photograph himself performing a variety of facial expressions. Although comedic, he can do them well.
I don't really think either of these were intended to be reference sites, but they're still pretty helpful. Enjoy!
That Eric kid rules!