[namelezz]

or Twitter - where most of these rejected people make awesome comebacks

[im2w1l]

Or, to account for the selection bias: People don't always come back after rejection. But when they do, they do it at twitter.

[autotune]

...which just laid off a bunch of their staff.

[siphor]

or Twitter - where the most engineers tweet

[fenomas]

or even: Twitter - where the guy who made this site works, with some colleagues he presumably asked to contribute stories