Usually Lego is a hobby unto itself. But what I really like are projects where the Lego is the means, not the end, where the project succeeded because there was this neato prototyping material lying around. Here are some good one pulled from the cobweb-strewn archives of Make: Online.

#10

Lego Letterpress

#9

LEGO Swimming Pool Insect Terminator (SPIT)

#8

LEGO NXT 3D scanner

#7

The Lego sequencer

#6

LEGO yarn ball winder

#5

Lego domino row-bot makes setup a snap

#4

LEGO PCB Agitator

#3

Lego printer powered by Wiring board

#2

Lego Technic camera dollies

#1