Small Rotation -> Linear Technic tip

Here is what I believe to be the smallest set of NXT-set parts that converts rotation to linear motion. Turning the blue axle jointer moves the yellow 1/2 bush along the worm gear, pushing the axle and the bent beam on it. Due to the properties of the worm gear, this is one-directional - pushing on the beam does not rotate the worm gear or move the beam itself.

Spring suspensions

wingnutamj has posted some nice Technic spring suspension. Find it here:
http://forums.nxtasy.org/index.php?showtopic=790&pid=6231&st=0&#entry6231

parts needed:

4 15N technic bars
4 pins (1*2)
6 large pins (1*3)
2 5N studs
4 pin stud things (see attachment)
1 rod extender (put 2 technic rods into it)
3 rod caps (1*1 circular pieces (full size))
1 12N technic rod
1 10N technic rod

Steering Mechanism of CAS

Here’re building instructions for the wheel steering mechanism from Bryan Bonahoom’s CAS (Collision Avoidance System). Notice that you must connect the motor rigidly to the two long beams when adopting this sub-assembly for your own use.

TECHNIC Treads

A good summary of market available treads by Brian Davis, with links to Bricklink where one can buy them.

Worm-Gear Motor “Multiplexer”

This design allows powering two different axles with one motor. When the motor rotates CW, the worm gear rotates only the front 8 tooth gear. When motor switch CCW, the worm gear moves along the drive axle, and rotates the far 8 tooth gear.