Was that an invitation? :-)

I'm not entitled to hand out invitations, but I've heard the pmdev is a fairly safe group to join; you can't destroy anything, just submit patches that a god can apply.

but how would I tell which project is most needed and worth spending time on?

Ask four monks, and you'll get a least five opinions. I think you need to be the judge yourself. Maybe your first project could be to set up a mechanism to determine which project to tackle next...