The Swingshot is an important gadget. If you see yellow or green floating orbs, you can use this. If there is a green orb, you can just press the button and go there. If there is yellow orbs, you have to swing across.
The Hacker is a way to get into locked areas. If you see a green pad near a door or gate, go up to it and press the trigger and solve the puzzle.
The Tresspasser is a device that uses lasers to bypass certain types of locks, Invinco-Locks to be precise.
The Hydrodisplacer This nifty device transfers water from pool to pool using special tubes.