http://www.catb.org/~esr/faqs/smart-questions.html
http://www.reddit.com/r/FOSSHelpWanted
http://sourceforge.net/people/
http://www.reddit.com/r/codeprojects
Outside of that, you'll want to know one or more of the popular Version Control Systems. Git is wildly popular these days, and subversion has a huge legacy base of projects using it. If you learned Git and SVN you'd be in good shape. But hg (Mercurial) and a handful of others are pretty popular as well.
For a good intro to Git and OSS projects, see:
http://codebetter.com/karlseguin/2010/04/22/contributing-to-...
Do you already code in one or more languages, or are you just now learning coding as well?
If you have any interest in learning Groovy and hacking some stuff that deals with the intersection of social-networking and information-retrieval, feel free to drop me a line... I run a project that could use some help.