I'm in my second summer of running a paysite and I have never experienced a seasonal slowdown (yet!).
On the otherhand when I was doing free sites and galleries, I used to see a summer slowdown in sales and revenue.
I think the difference is due to recurring billings and the holdback. With my paysite, my recurring sales, as well as my 5% holdback, act as a "dampener" and shortterm declines in new sales aren't even noticed in the revenue.
But for my freesites most of my income came from flat fee sales ($35 to $42 bucks per sale up front), as is the case with most guys. So you really notice any drop in sales as significant drops in revenue. And like I said this is what I used to experience with the major sponsors in July and August - especially last year - 2001.
I think this accounts for most of the ongoing debate about "is there really a summer slowdown or is it a myth?"
Generally, paysite owners don't see it, but most freesite guys do.
That's my

on the subject.