There are several properties in Facebook official pages that you can use as marketing billboards. One of the best spaces available is the profile picture. To maximize the space make a 540 x 180 pixels vertical banner. Don’t just grab a random photo and upload it as your picture. Make the most of the space available. This is something we actually still have to apply to the NMP page (haha). Anyway, here are some examples of well designed profile pictures:
Note that you can use this space to promote the fans of your community as well. You can put the picture of your “customer of the week” and just edit the photo so that it fits the dimensions provided. As Facebook evolves make sure to keep an eye out for changes that will give you more ways to market your promos, events, and products. 
isnt it 200×600?