You and me both, Alisa.
I don't think website developers have studied this issue as thoroughly as one might think, though. Some advertisers/marketers, yes, but I think a lot of web admins just do what they've seen done elsewhere, and there's a lot of experimentation going on.
I think Google actually did a study that supported the effectiveness of their text-based ads, and I also seem to recall some study supporting "pop-under" ads, but I don't remember the details.