I love a lot of the complex, massive LEGO robots out there... but sometimes what really impresses me is thinking outside the box. I recently ran across this example of using the NXT as anything but a "toy"... but as a serious way of rapidly generating a solution to a real problem.
This group needed a way to torture test a DVD player, and rather than generating some special solution, they turned to the NXT, and quickly tossed together a solution to the problem. When the player ejects the DVD, the NXT robot gently grabs the disk (sensing it with the light sensor), and then after a short time reverses and re-inserts the disk.
And when they're done torturing the drive? 100% reusable parts. I like the way they're thinking.