This is a really interesting subject Phillip.
I've noticed that the two main types of ads tend to be either the ringtones or singles/dating ads (which sometimes can be sort of amusing and some can be a bit cringe-worthy). I remember a while back there was a flashing pink ad with some images of a woman in stilettos crouched down that was, frankly, a little hard to deal with on the computer at work (because the pink combined with the flashing was so glaring).
And, we had a discussion once somewhere about what the "Michelle Williams" ringtone really means... and if it could possibly relate to some of Alma's classic lines from BBM.
It was pretty funny.
I'm always amazed at how specific some of the ads can be in relation to the content being discussed. A while back in the 1000 Posters Club, we were talking about window air conditioners, and like clockwork, ads for air conditioners started appearing.
One thing I do find difficult, is the proximity of the ads to the scrolling bar... it always feels like it would be too easy for a hand to slip and to click on an ad by accident. I'm actually surprised at how rarely that happens for me.