Here is a list of 4 Free SVN clients available on Mac OSX. I couldn't find one that integrates in OSX's Finder though; some time ago I wrote a post about SCPlugin, which integrates with the Finder right-click a-là Tortoise. Well, even if it's a discontinued project, and it doesn't have all the advanced features of Tortoise, I still use SCPlugin for my basic SVN tasks.

For all of you looking into something more complete and free...
Here is something ready to download!

ZigVersion
zigversion


Bazaar
bazaar


SubCommander
subcommander


RapidSVN
rapidsvn