Possible Duplicate:
How does Stack Overflow, Meta Stack Overflow, etc. make money?

There is this BIG network: Unix, Super User, Android, etc. There have to be big [?] servers behind these websites that are hosted at XY place. This costs money. Where do the Stack Exchange guys get all the money for this? From donations? I can't see any ads on the websites!

I'm just asking, because it's an important thing in the future to be capable of serving all the growing interest in these kinds of websites! For example, Wikipedia also advertised that it needs donations and whooosh, donations came!