I've always loved the animated shorts that Valve come out with, especially the Meet The.. Series with Team Fortress 2 Characters.
Meet The Soldier:
The whole animation style is very 'cartoony' and fits well with the scenes which are simple but not at all plain. The lip syncing on this particular video is fantastic! It has to be since his mouth is the only part of his face you can normally see. I like how they've animated a sort of verbal personality into his mouth. His mouth 'E' shape is exaggerated and they've given him a bit of an under-bite. My lip syncing is pretty basic right now but I'm starting to work smiles and other emotions into the mouth while talking. I want to start putting in more personality when I think the character would have a particular way of speaking.