I think Flash looks good in banners, but when I go to a site I want to see what I went there for. And be sure it's not to be impressed by a designer, especially if I've got my dick in my hand.
The problem is we all feel the most important thing about a site is what we are best at, designers think it's got to be great design, I think it's the porn, traffic guys say it's the hits.
Look at some of the top sites and see how they do it.