Snap Inhale
The "Snap Inhale" is a fairly complicated trick and may take some practice to master. Start by taking a toke. Then, while the smoke is still in your mouth, curl your tongue upward towards the roof of your mouth. Next, open your lips a bit and snap your tongue down. Finally, let the smoke float out of your mouth for a moment before you quickly inhale.
French Inhale
This is a very cool technique that will prove you are a pot-smoking pro. Simply take a nice hit and then open your mouth (letting the smoke flow out slowly). Then, lightly inhale that smoke through your nose. If done right, the smoke will gradually flow out of your mouth and directly into your nose. After the initial inhale, you can draw the rest of the smoke into your mouth or continue to inhale through your nose until the hit is completely finished.
Smoke Rings
Ok, this is one of the coolest tricks, but also one of the most challenging. Take your hit but don't inhale the smoke. Form your lips into the shape of an "O" as if you where gonna say "oh". Then, quickly push some of the smoke out with the back of your tongue as you exhale. A tiny puff of smoke should emerge in the shape of a ring. Once you've got that down pat, you can change the size of the ring you exhale by varying the amount of space between your lips. (Also, you can flex your throat muscles rapidly and shoot out rings in rapid-fire bursts.) Finally, when you become an expert at the basics, you may be able to shoot out a large ring and then quickly send a smaller ring speeding through the center of the large ring.
The B-Bomb
For this one, you need to be sitting at a table or something of that sort. After you take a huge toke, stand up and go about 6 inches away from the top of the table with your face and breath out the smoke. If you do it right it will look almost like an upside-down mushroom cloud.