VisualSVN Server - Get an easy to use Subversion (SVN) server for Windows. It works out-of-the-box and is suitable both for small business and enterprises. Available for free!
TortoiseSVN - The coolest interface to (Sub)version control
uberSVN - Free, easy to implement UI for Subversion which includes:
VisualSVN - VisualSVN - Subversion plugin for Visual Studio
Slik SVN - SlikSVN is a free subversion client for the command line.
GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.