InstantMines is my first Bukkit plugin. Whilst simple it's also light and hopefully useful to someone other than myself.
To make one a mine which has configurable block and player damage make a tower as described below:

The iron block is intended to prevent users from unwittingly creating an instant mine when simply trying to power TNT with a pressure plate from above.
To create instantly detonating TNT, which is pushed into a powered position by a piston, change the tnt.delay value in the configuration. 80 = default, 0 = instant. Example piston setups.
Any feedback is welcome.
Just pop the .jar in your plugins folder and restart/reload.
Thanks for reading,
Steamy