[billy99k]

I know of two: Craigslist and Plenty Of Fish.

[zavg]

Are they 1-person projects? Also, Minecraft was build solo by Notch, I guess.

[homarp]

https://en.m.wikipedia.org/wiki/Mojang_Studios helped with minecraft, even before the MS purchase.

As an employee of Mojang Studios, Jens Bergensten had been co-developing Minecraft with Persson since 2010.