@Aaron D. Campbell - Well, not all Flash ads are equally annoying ;)

I have made quite a few web ads at my day job. I often use animated GIFs and Flash for these ads, but the animation is slow, the transitions are soft, and they are not content heavy.

I think just about any non-popup/under ad format is fine, as long as the ads are made to be subtle and not overly annoying. Unfortunately, it is much too easy to make those kind of annoying Flash ads that we are all very familiar with!