Review for Just Restart! by strelnic
Rated 5 out of 5 stars
Just this
Also adds a File menu and main panel item.
Can be manually modified easily to use another shortcut changing this line:
<key id="key_just_restart" key="Z" modifiers="accel,shift" command="cmd_just_restart" />
into just-restart-fx.xul and just-restart-tb.xul under chrome/content, removing META-INF folder (signature), and zipping everything to an .xpi.
To create your own collections, you must have a Mozilla Add-ons account.