It's circulating over the net today that Google has given themes to select Gmailers. So check under your Settings tab and and see if you have a Themes tab now. You may be a lucky one! No more boring background, yay! Below is more of a full list of what's available. There are a total of 30 backgrounds.
, Gmail blog
If you don't see it today it may pop up suddenly in the next few days. And then YOU too will be the chosen one!