The obvious answer is "advertising" but I've heard of a lot of decently popular sites that don't make much on advertising. How else do you make money? are they just hoping to get bought out? And for ...
Paypal's simplest integration is an IPN and is super simple, but we all know the risks, and how badly they handle monthly billing. But it takes an hour to set up and is $.30 + 3% or something. It ...