I find that happens to me all the time...it seems like it's nearly impossible to surf the web, even on seemingly "friendly" sites without being bombarded by this kind of crap. It really makes me mad sometimes.
Maybe it's time to make a new homepage
Google news is a fairly clean and harmless homepage I have found.
For those of you using firefox, I found a nice plugin called AdBlock which disables many ads on the internet, and is free. This might be a help to some out there. If you don't use firefox I bet there are other programs which could do the same thing.
Good luck!