Audio Vampire is a full-fledged audio editor. It can record any sound played on a PC, including VoIP calls. Skype, MSN messenger and Windows Live Messenger are supported. The sound quality of VoIP call recording is superior to other programs. It does not use the Skype API. The maximum recording length for VoIP calls is 3 hours and 20 minutes. Other audio sources can be recorded until disk space runs out. Also, Audio Vampire has an extensive range of sound editing/effect capabilities. It can even rip CDs. Check it out.

Audio Vampire is a shareware program, made by TechnoCraft.
Download the trial version from:
http://www.technocraft.co.jp/av/eng/