looking for stretched art(designing xbox background)


I just found out you can design your own Xbox 360 background, and I am looking for ideas.

It has to fit in the white area of

I was thinking of something grand and pretentious, but seeing I don’t know much about art, I thought that maybe you guys could give me some ideas

I like loud and bold but I am open to sugestions…
*bonus question, what proportion am I looking for? 1:4 or something?