Ah yes, 'million pixel' sites, they have been around for a very long time and everytime I came across one, for some reason I used to get steamed up, I guess I had a really bad anti-pixel ad disease. These sites are probably the worst method of advertising after safelists and spam!
I'm one of those people who hates pixel advertising a lot. The only pixel advertising that I have tried was the section in DirectMatches where you get a certain amount of squares depending on your subscription with them. In all my months with being with them I've only received 4 clicks on my 4 pixel ads, and I think I was the one who clicked them to check out if my link worked properly
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If I come across any pixel advertising site, I run the other way, there is a benefit to the website owner, but think of the traffic you will get.... horrible!