BugKick is an AGPL'ed bug tracker (with a hosted option.) Not that we need another bug tracker (especially given my Codes Well With Others ranting) and especially not one written in PHP... but the kickstarter itself is only aiming for a tiny amount of funding to do a couple of months of polish work (and presumably to find out if anyone cares) which would be a novel data point in the kickstarter software funding curves. (not yet funded; not backed)
Liederboard is an HTML5 sheet-music scratchpad with visions of user generated content :-) It made the initial funding target, has delivered some features already, and has a decent tech blog about the progress and goals. Not open source, but an interesting example of reaching a niche audience with a somewhat unique piece of software, and putting it all together and actually funding it. (funded to initial target, long list of stretch goals available; not backed)
Mission: Escape uses the GPS in an iPhone to track your driving, and produce an on-the-fly soundtrack for your commute. That just sounds like a lot of fun :-) (not yet funded, not backed)