This looks like a great service. There doesn't look like there's a way to post a bounty for a repo that's not already signed up though.

There used to be a Signal project on Bountysource with a bunch of pledged money, but I can't find it anymore. I had pledged. Odd, I can even find the PayPal receipt for my pledge.

Edit, found it: https://www.bountysource.com/teams/whispersystems the old links did not work