A conclusion about banner ads
 

300 x 250 are way better than 728 x 90

banners you say? :)

it all depends on where you put them on the page, really.... and of course, the effectiveness of the banner, as in does it make them want to click the ad?

480x60 and 120x60 work best for me. I also like to put 120x600 between rows.

Size doesn't matter :Graucho

300x250 gets the best CTR (usually) of any other banner size online across the board. Also, it tends to convert better. However, there are some exceptions as every ad buy and placement is unique.