CVSNT is a CVS clone. CVSNT features are:

* Merge tracking via MergePoint attribute.
* Support for :sspi: and :sserver: authentication.
* Branch ACLs can be used to restrict access.
* Directory browsing via cvs ls command.
* LockServer on a second port replaces filesystem-based locks &
  provides file level locking.
* More sophisticated / extra triggers available e.g. postcommit.
* Supports Unicode files with additional keyword expansion switches.
* Atomic Checkout behaviour ensures you get the right version of every file.
* Efficient storage of binary files using binary deltas. 

WWW: http://www.cvsnt.org/