Unicraft Joinery of Hamilton, Victoria, Australia made this wonderful staircase with drawers hidden in each riser. I'd hate to go down it in the dark with the drawers left out, but a few broken necks would be a small price to pay for all that storage. Link (via Digg)
Update: Jon sez, "I've seen this in houseboats where they need to use all the space as efficiently as possible. I've also seen where about three steps all hinge upwards revealing a big storage box underneath."