I can not believe some of the following projects are made from cardboard!  Here is a roundup of cardboard projects with everything from fun to functional.

D.I. Whut? Cardboard Furniture via Regina Galea
Cardboard Radio via Urban Outfitters
Recycled Cardboard Window Valance via in my own style
Cardboard Faux Logs via Design*Sponge
Hex Light via Von Tundra
Wall Hanging Box Aquarium via Made by Joel
3-D Cardboard Star via grey luster girl
Moon Scraplights via graypants