Any blocks connected to the motors will not collide to the another model being motored. They are commonly used for cars and technology.
Very common with cars, when the game started the wheel will push down a quarter-block.
Rockets can be used any time an object is needed airborne. They have two commands: to either fire which causes them to provide thrust, or to smoke, causing them to simply output smoke but not provide any thrust.
Levitators allow an entire structure to lose its gravity just by attaching it and setting it to levitate. They can be used to steer, lift, or even to point directly at a chosen object.