I collected some videos about facial animations through FACS (Facial Action Coding System) in real-time for virtual characters: http://www.youtube.com/user/docnero#grid/user/8A4CC39781EBD595
And I also like the system done by Nicolas Stoiber that recognizes the current emotional state through facial expressions from a user mapped to an emotion disc and mimicked by a virtual character: http://nicolas.stoiber.free.fr/research.html