What it is.
Run /instaboom. Place a block of TnT. You might want to run. KA-BOOM! Welcome to InstaTnT, a seriously fun plugin!
Download and drop into your plugins directory
Edit config, restart again (This step is optional)
I have re-coded the plugin. The command is now /instatnt, and I'm working on an update that adds permissions.
No longer inactive, bonus!
New GitHub repo: https://github.com/sam4215/InstaTnT-Bukkit