I recently made the jump to using Subversion as my version control system for my various software projects. If you haven't made the jump I'd recommend you consider it and say goodbye to all your CVS headaches. Check out this article on Subversion tips for CVS users. If you use Visual Source Safe you have my sympathies and you have even more reason to checkout Subversion... (yes that was a horrible pun)
But this post isn't about being a Subversion cheerleader, it's about finding good tools for Subversion on OS X. You can install Subversion for OS X by downloading Martin Ott's Subversion package. This will give you the command line subversion tools, but who wants to work solely on the command line? Thanks to a post by Boris Mann I found out about SvnX - a nice GUI front-end for the command line tools. Install both these and you have some nice tools to work with Subversion. The best part it's all free.
I also found a Subversion client for OS X called SCPlugin that integrates into the Finder similiar to TortoiseSVN for the Windows shell. It looked pretty cool BUT it doesn't appear to be in active development. The last news was from 2004 so I don't know what state the project is in. I was scared to install something that integrates into the Finder that might not be stable...