Advice from the pros:

• Your new desk can be nothing more than a couple of standard filing cabinets (shot with Krylon) with wheeled stands attached to their bottoms for easy moving. 
• The desk's top? A chunk of melamine.
• When decorating, treat the inside of the closet like you would a room. In this case with wallpaper and paint.
• Skip bracketed shelves and opt for floating shelves for a less-cluttered look.
• Make use of every inch of space with peg and cork boards.