I'd be interested in contributing to an open source project, but don't have a clue where I could find a project thats looking for people. Is there a site that lists open ones and what they're looking for etc? I'd be particularily interested in java projects
Usually theres is a section called "help wanted" in most open source projects.
Look for that section. Let me see if I can get some for you.
Here are some: http://sourceforge.net/people/
Others here:
Rather than search for projects that need help, I would find a project that you are interested in and use, then check their issues/bug database, find a bug, fix it and submit a patch. Repeat until the team gets to know you, then ask to join.
If you just pick some random project that needs help, you are probably not going to stick with it for long. You need to be interested in the project you are contributing to and the best way to maintain your interest is if you actually use the software you are working on.
Update
There is now an open source website called Up For Grabs where you can find open source projects that are looking for help and have labeled some of their bugs as suitable for new developers. I still stand by my original assertion that you should follow your interests, but this website can be a good starting point.
Most open source projects need some kind of help, so the odds are that your preferred open source application is one of them. Instead of going looking for some random project that needs help, just take some piece of code that you use frequently and offer to help. Try improving the docs that you had difficulty with when you were a newbie, registering and discussing something that bugs you, going to the issue tracker and working on some bug that bothers you or asking in the mailing list what you could help with.
Do the usual open source thing and scratch your own itch. You'll be a much better contributor on a project that you care about than you'll be on some random project that you happen to pick on the street.
The biggest open-source site is sourceforge.net (mostly *nix). Growing in popularity (and more .NET oriented) is CodePlex
While this question is different, the answer is the same.
What is a good project to work on to learn modern patterns and practices?
Find a community service organization that needs help.
来源：https://stackoverflow.com/questions/335889/is-there-anywhere-that-lists-open-source-projects-looking-for-contributors