Unfortunately it's not profitable and I'm not even sure I'd call it a "startup" but I do have a day job and enjoy building web apps in my free time. My most recent project is http://www.famsnap.com. I built it after becoming frustrated with the process of finding a photographer to take family photos while we were on vacation.

I have around 300 members currently but it has been slow growth. Every photographer I've told loves the idea but there's no place to really promote as posting on Facebook groups or forums is seen as spam and deleted. So I'll keep on growing slowly I guess using Instagram to contact photographers and see where I am in a few years.