A few days ago, I found myself on a Facebook fan page with a huge banner going down the side of it, instead of the usual small avatar picture. It looked so great that I had to ask how she accomplished it.
Turns out, Facebook won't crop images that are 200wide x 600 long! That is it, nothing tricky to it.
Try it out, it is a lot of space to market yourself and really personalize your Facebook page. Check mine out at: