Bulent's Screen Recorder is an excellent Windows program to record, for example, an MSN Messenger or Yahoo webcam session. Sadly, the author decided to make the more recent version shareware. However, I consider the program well worth the money. Good news is that the new version also supports audio recording.

Besides recording webcam sessions, the recorder can also be used to record computer instruction videos, for example you can record the installation and usage of a program as a movie, or even web based security cams.