Let me refer you to actual research :
http://www.zenofeller.com/clickmystery.php
So, total ecommerce, 25billion a quarter, 275million or so a day.
I'd guess google/adbrite etc take most of the pie. I'd guess amazon etc take a good chunk too. I'd guess the guys selling computers and corporate shit take most of the rest of the pie.
Adult probably has a decent share of it, GFY-type adult (yes, by that I mean smalltimer types like yourselves who think wealth = house, car, house, car and dominican cigar) may be .1 to 1% of that, probably closer to the .1.
That's 3M to 275k a day. Taking 30$ as the average payout for a join, you're looking at 100,000 to 9500 joins a day, or about one a minute.
Which somehow sounds about right.