If you're looking for something to build this weekend, Instructables has you covered: Cardboard Lumber. The text on the glueing step is the best:

Lay our your cardboard on a flat surface and get your first layer ready. Apply a VERY large amount of glue to one section by POURING it on the surface and spreading it evenly. If you think you used too much, then you almost have enough glue on. Now apply glue to the piece to be put on for the second layer. Don't think of this as glueing cardboard together! Think of it as paper mache WITH cardboard! Lots of glue!

And in that vein, does anybody wanna silkscreen up some Core77 t-shirts for us?: "If you think you used too much, then you almost have enough glue on."