We developed a few tools that we use ourselves and don't mind to share. As we often work on PHP projects these are all php based.
To guarantee transparency we developed a tool to check in done hours. This is important to report the done work to the client and very usefull for the freelancer to keep an over view about the progress of his work.
Due the popularity we moved this tool to its own domain and open it up for everyone. --> melancer.com
smarty language string management
There exist a few hacks to make the smarty php templating engine multi language capable. We wrote a web interface to manage the language strings (.po file) for that. This can be used either as an internal tool, or as an open comunity based tool. What it does, it creates the .po files of the fly and add's versoning and discussion functions.
It is very similar to the lauchpad translation tool (at the time we wrote it, lauchpad was still closed source ;-)