Did you know that you can buy a Brad Pitt-designed diamond ring from Italian jeweler Damiani? Or that jack-of-all-trades P.Diddy designed his own SUV -- the Lincoln Navigator Sean John Edition (pictured) -- that you can own for the bargain price of $85,000? Even teen queen Hilary Duff is in on the action. Her clothing and accessories line, Stuff by Duff, is a must-have for tweens. We've been keeping track of what the celebs are hawking. Have you? Test your knowledge of celebrity "stuff" right here.
