mergesvn (not to be confused with svn merge) is a simple tool I wrote to resolve conflicts in Subversion working copies using the Mac OS X FileMerge application.
Given the name of a file with conflicts, it automatically finds the ".mine" and ".rN" files svn creates for a conflict. Saving the FileMerge window will overwrite the file; you must do svn resolved yourself. [Update: The above-linked version will run svn resolved for you.]