REPEAT: "We are busy people just trying to use a tool, don't make us spend even more time on the tool itself!"
- The usual ones: open-source, cross-platform.
- Everything from Subversion, using subversion filesystem as underlying storage.
- Trans-backend mirror.
- Use svk today to work with Subversion, cvs, and Perforce repository.
- History-sensitive merge.
- History-sensitive patch.
- no .svn/ nor CVS/ everywhere.
- Painless vendor branch management.
- Interactive conflict resolution.
- Changeset signing.
- Should already be in your distribution as binary package.