Apart from those already mentioned, I have my SVN install integrated with Mantis, its straightforward, but I did modify my post-commit hook so it tries the regexp in the hook to check whether to update a bug or not (for performance).
I also use Doxygen to build documentation for my code, its triggered from a post-commit hook too. When a directory with the x.doxy config file is committed, that directory is written to a file and a cron runs doxygen on a export of those sources at midnight.
