Ask HN: Bug hunting / open source for a living

I have been curious if it is a reasonable goal to hunt bugs / develop for open source projects for a living.

Are there are any sites that have a "bounty" board for bugs and is it possible to make a good living hunting bugs?

Also, does anyone know of a good and active open source C# project? I want to spend some time contributing back to the open source community as I have used many open source tools and gained much knowledge through studying them.