Most of the more "hip" websites I use (Wikipedia, music trackers, occasionally webcomics, the smarter blogs and startups) have abandoned banner ads in favor of periodically relying on their users to donate or pay for extra features. Much better business model. It's important to remember that business models with regard to the internet are still in the early trial-and-error stage. It took the automobile industry a while to get it right, etc. There's a natural evolution to these sorts of things.
Wikipedia is a poor example, considering that it takes months of annoying banner ads begging for donations before they are able to make their fundraising target. They would undoubtedly have an easier time getting funds if they ran an advertisement or two on each page.
Wikipedia is a perfect example, because they refuse to sell out and possibly sacrifice the validity of their content for easier money. Best business model choice they could have made. Now that is Web 2.0 if I ever saw it. Their system works perfectly, and anyone who is annoyed by that banner has some problems.