TracExplorer is a collection of utilities which integrate TortoiseSVN and Visual Studio 2005 and 2005 with Edgewall's Trac system.
Aigenta Unified SCC adds seamless integration with Subversion/SVN and CVS to IDEs which support Microsoft's SCC.
Unified SCC adds seamless integration with Subversion/SVN or CVS to your development tools of choice.
CQ2SVN provides complete integration between Subversion and IBM Rational ClearQuest.
VisualSVN is a Subversion plugin for Visual Studio which uses TortoiseSVN for its UI.
It is not free.
The Pushok SVN to Microsoft SCC provider is a plugin for your IDE which integrates the Subversion version control system into the IDE.
The sourcecross is a Microsoft SCC provider for your IDE. I cannot find a download for it at the time of writing (12 April 2006).
This project appears to be dead as there has been no activity on it for some time.