My two main work surfaces are a super-fun peanut shaped red table and a super-functional unconventional workbench. The peanut table came from Ikea; the unconventional workbench was pieced together from pieces found at Community Forklift, a great surplus, salvaged and green building material supply center.
The top of my bench is a solid wood door (which just happened to exactly match the closet doors in my house). One "leg" was the base of a kitchen cabinet; the other was intended as a hanging unit. Together they make my workbench the perfect height--comfortable to stand at while working.