Everyone knows of Flippa for buying and selling websites, but is there something like this for smartphone apps? Is there even a market for flipping apps? I'm just wondering because I'm about to start getting some apps of my own developed and if I want to sell them in the future for some reason, I will need a place to list them. I tried searching Google and did turn up a few marketplaces, but none of them seem very active at all. Do any of you know of some good ones?