Interested in Joining an Open Source Project

The last few years I have grown accustom to using open source software. Lately, I have been thinking that I would like to give back in someway to the open source community. While financially I can't really afford to donate money to something such as the gnu project, I could donate some of my time and work on an open source project.

I'm not really sure what is the best way to go about getting involved in an open source project. Should I go to a site such as freshmeat.net and try to find an interesting project and email the authors of the software to see if they need help? Are there any other sites I should use to locate potential open source projects to work on? I basically would like to know where is a good starting point for get involved in a project and see if anyone has any recommendations.

I am fairly inexperienced with working on large projects. I have experience programming in Java, C, and C++ but only in a academic environment. I'm always trying to learn new things about programming and I think the experience of working on a project would benefit both me and the users of the software. If any body has any suggestions let me know I highly appreciate it.