CVS is an acronym for Concurrent Versions System, and is the time-honored multi-platform version control system used just about anyplace you care to name (at least until Subversion takes over).
Resources:
Tools:
- CVL
- CVSspam - CVS to insanely colorful HTML mail.
- CVStrac - my personal favorite, used on the CVS Section of this site. There's also a pre-built binary for Mac OS X.
- CvsGraph
- ViewCVS
- StatCVS
- TortoiseCVS - for Windows