Many people have been using small banners or just logo images to the left and an adsense or some kind of ad to the right. Large banners are somewhat dated and smaller ones similar to the top of the Hubpages site is much more common.
In the older days of the internet it was important to have a large header as people spent up to 25 times longer on any given page then they do now (thanks to faster internet speeds). I remember when I was 12 on AOL Dialup and if the whole page loaded before being kicked off it left a good overall visual page to look at before having to hit reconnect and have the dialer dial and wait for it for 2-3 minutes before being connected again.
Also, due to these speeds more images can be used in the content so boring text pages don't have to be boring...and texty.