Vault VCS - SourceGear Vault Pro is a version control and bug tracking solution for professional development teams. Vault Standard is for those who only want version control.
SmartSVN - SmartSVN is a graphical client for the Open Source version control system Subversion (SVN).
Microsoft Visual SourceSafe - Microsoft Visual SourceSafe (VSS) is a source control software package oriented towards small...
TortoiseSVN - The coolest interface to (Sub)version control
Mercurial SCM - Mercurial is a free, distributed source control management tool.
Xversion - Super easy enterprise class version control.