Almost every project needs volunteers. Many have died because the original developer gave up on the project. Others move very slowly because the original developer does not understand the details necessary to make the next step (e.g. how to package the software into an rpm). Many are active and all you have to do is start working on them. Fedora, RedHat's new open source project, has no official ``developer'' status and anyone can work on it even though Fedora is a major distribution from the largest open source software company.
So you could, without asking anyone's permission, become a developer on the world's largest software distribution before the day is finished. Within a few days you could perform a valuable service. For instance, Fedora needs quality assurance testers. That basically means that you have to download, install, and try to run various pieces of software. If you find a bug you report it. If you find enough bugs and learn to file sufficiently helpful bug reports, your name gets known as a useful tester.
Or perhaps you speak two languages. You could pick projects in the Fedora distribution, modify their error messages to be in your second language. Soon you will be known as ``the internationalization guy on Fedora''.
The key point is that you decide to participate. You hire yourself.