TortoiseSVN - The coolest interface to (Sub)version control
SnailSVN - Similar to Tortoise SVN for Windows but integrated into Finder
VisualSVN - VisualSVN - Subversion plugin for Visual Studio
Xversion - Super easy enterprise class version control.
Slik SVN - SlikSVN is a free subversion client for the command line.
kdeSVN - Comfortable graphical SVN client for linux.