TortoiseSVN - The coolest interface to (Sub)version control
SmartGit - SmartGit is a front-end for the distributed version control system Git and runs on Windows, Mac OS...
SnailSVN - Similar to Tortoise SVN for Windows but integrated into Finder
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
RapidSVN - CollabNet, Facilitating Collaborative Software Development
SourceTree - Mac and Windows client for Mercurial and Git.