I've used Photobucket for years. Never had a problem, and it's free. And I've never seen a "pop up" ad. Yes, they have static ads, but if I can get free photo hosting in exchange for an ad or two on their home page... fine by me!
I have to wonder why people will pay for Fotki when they can get the same from Photobucket for free??? Oh well, it's your money, guys.