So I was messing around on single player and found something cool yet pointless to do with TNT.
You will need:
[font=comicsansms] Redstone
Redstone Comparator
Water Bucket
Obsidian
TNT
Dispenser
Lever
[/font]
Step 1
Build what is show below. Check that the end of the comparator with one torch is lit.
Step 2
Fill the dispensers with TNT.
Step 3
Turn on the lever.
You will be continuously lifted in the air, until the TNT spreads and blows up the circuitry.
Its kinda pointless, but fun :)