Last year Angie Taylor posted Lip Sync in After Effects, teaching a task that most animators will be asked to do at some point.
The technique in this video (from Adobe After Effects CS5: Learn by Video) automates the process and uses only built-in features of After Effects CS5. Tutorial files and a text-based version of the tutorial (from AE 5.5) are available if you want to follow along with older versions.

