this is the best one yet the TNT NUKE!!!! first you will need lots and lots of TNT and stuff to build a town
step 1 dig the place where you want the town save the dirt about 5 blocks down
step 2 4 blocks down put the tnt leave a bit of tnt showing but make it level with the dirt
step 3 where the tnt is showing make a nuke have it out of logs for best results
step 4 once you have a holowed out nuke put tnt in it then 1 lever on the side (or make a redstone wire so you wont die)
step 5 now build a town on top of the underground tnt range (you might want to make the town look awsome so players will miss it when it blows up)
step 6 put some deco up and voila! you have a nuke testing ground!
role play tip if you detonate it have the player(s) who set it off stay behind like
the town has a curse! and 1(4) player(s) have to kill themself(s) to save a group of people.
its good to do it on your server so other server admins dont get pissed off at you
dont have one? do it in SSP mobs will love you for that

based on fallout 3's "megaton"