going back to one of the first posts about facial muscles, here is a nice little flash movie that lets you overlay each of the individual face muscles over the head to get a better idea of where they are and what they do. There's also info on expressions and which muscles are involved in what:
https://www.artnatomia.net/uk/index.html
(click the application link to the right)
Si
p.s, it runs as an swf flash movie so you 'can' (even though I wouldnt condone it other than for personal use) grab a copy from your browser cache and use it offline as most of it is contained in the single swf.