If you have advertised using banners or place banners on your site as a publisher you are probably aware of the Interactive Advertising Bureau (IAB) and their Ad Unit Guidelines. The ad unit guidelines show the sizes of the banners expressed in pixels. The reason for guidelines is to make it easier for publishers and advertisers to do business. The publisher states which size banners (in pixels as well as file size), format (such as .jpg / .gif), type such as animated or not and using which technology, and the basic information is common knowledge to everyone thanks to the IAB. These banner sizes, in pixels, have been around for quite a while. I may be mistaken but I believe the first commonly accepted banner was the 468×60 and I do recall using LinkExchange (years ago). Here is a random fact, did you know the CEO of Zappos Tony Hsieh started LinkExchange? He did. So now the IAB is considering adding additional sizes to the common banner sizes.
Ad Unit Format Competition
You can read more about the Rising Stars Ad Format Competition put on by the IAB. If you have ideas, and particularly if you are a designer or have been creating banners for years and always felt restricted by the size, or functionalities, page integration etc., then take a look at the competition and suggest your best format. It is worth a shot, not just to potentially win a competition but to affect the overall online advertising industry for the better.