For the last ten months or so I've been working essentially full time on a webapp. The webapp doesn't make much money (through donations it covers hosting costs and allows me to go out to lunch daily). I'm not bitter about it. I knew it wouldn't be profitable, but it was a labor of love and I plan to continue maintaining it when I get a job.
Would it be alright to list this under professional experience? I mean, I learned a ton, and the site is live and has a decent userbase.