A link to this 2006 blog post came up on my feeds recently :-
It's a great article (with excellent commentary) on reasons for (and against) starting your own code project versus joining an existing one. Things are certainly not as clear cut as they might appear at first. It uses the umpteenth Python web frameworks spawned (prior to the arrival of Django) as a basis for discussion but is good general advice for those thinking about contributing to the pool of open source software.
Certainly food for thought.