I just got this: Amazon.com: Arkon Portable Fold-Up Stand for Apple iPad, Galaxy Tab, BlackBerry Play Book: Electronics
I like it. It folds up very small, but it's very adjustable and sturdy-feeling. The Xoom fits nice even with a gel case, and the bottom of the stand is anti-slip.
Good price on amazon, plus prime eligible (I actually ordered yesterday, and got it in 1 day with the 2 day free shipping option. score!)