What fun! We've recently done the same at my work - I moved from my won office to a cubicle situation. All I had on my little wall was a calendar, with small animals on it... so I could write in all the things I had to look forward to outside work. Mostly Vanessa Amorosi concerts lol.
I reckon you should be able to put anything... but beware of posting up swimsuit models and the like. It's a standard and expected thing in the military, but not sure it would go down so well in a civvie office