I've got a site that gets ~10,000 uniques per month (www.area51.org), and I still have never found a way to make much money at it. Yes, I've got ads. And yes, I've thought about affiliate marketing. But I wish I could bust out of my boxed thinking and come up with some revenue model that's more compelling.

(On the other hand, the site is self-sustaining; I don't have to think about it much.)