You could sign up at SourceForge.net and check out the help-wanted page to see who needs a hand, but please be a serious coder before you commit yourself to someone's serious project.
All to often this kind of thing pops up:
<nucoder> hi! ready to code. where is the source?
<PrjMgr> Log onto the cvs server at dev.blahblah.example.com and check out the module Revision3
<PrjMgr> Steer clear of the head branch for now. It's full of garbage
<nucoder> uhm.. what is cvs?
<DsgrntldDsgnr> Freaking noob. f-ing google it!
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6 months later
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<PrjMgr> nucoder, when are you going to commit some work?
<nucoder> sorry. have rl issues right now
/me cries