Facebook's number of active users served per employee is very impressive. The ridiculous number of photos uploaded every second.
I've long ago figured out that I'd never be able to pass the screens for Facebook, Apple (and at one time, Microsoft). I do still dream of Apple, even after reading the $0.99 Fortune Kindle single on how 'it's not about getting hired at Apple, it's about being able to stay'
What makes me happy however is creating apps that people use (and sometimes even enjoy using).