If a contributor includes a public scm in for their contribution, someone should be able to grab a compiled swc from the latest source.

This would be like a vote for a project, you could call it either: up-vote, recommend, or I-use-it, or maybe something else still, each has it's own implications. Then you can build a recommendation system based on this: people who use this project also used ...
Also, take a look at ohloh.net for some ideas.

That way people can see what the best alternative is