TortoiseSVN - The coolest interface to (Sub)version control
kdeSVN - Comfortable graphical SVN client for linux.
SnailSVN - Similar to Tortoise SVN for Windows but integrated into Finder
Xversion - Super easy enterprise class version control.
eSvn - eSvn - a GUI frontend to the Subversion revision system. With eSvn you can:
Slik SVN - SlikSVN is a free subversion client for the command line.