We launched Geocodio [1] in January 2014. It's a side project, so the definition of "profitable" is a bit different, but it's paying for itself and then some -- servers, Basecamp, LLC filing fees, etc. We're making enough that it covers costs for other, less serious projects [2][3] and our "fun" server (for testing out new projects/ideas/etc) with some to spare.

This was our first time launching a serious product as a side project and it's been a blast. I actually wrote up a few thoughts on launching side projects last week [4], largely based on our experience with Geocodio.

[1] http://geocod.io [2] http://opennear.by [3] http://happykitchen.dotsqua.re [4] https://medium.com/@mjwhansen/things-ive-learned-launching-a...