NOTE: This add-on is now unmaintained! You should use this one instead:
Crash Me Now! (Simple)
The Electrolysis ("e10s") project allows Firefox to separate web content from browser chrome, and also makes it so that if a tab starts to misbehave, the tab can crash instead of bringing down the whole browser.
This add-on induces a tab crash by sending a frame script down to the current tab's content process which uses js-ctypes to de-reference a null pointer.
The script is triggered by way of a button added to the toolbar. The button has a mushroom cloud on it.
Mushroom Cloud designed by Gilad Fried from the Noun Project