nice to have Bewertet mit 4 von 5 Sternen

you never know when your roomate's going to get back from class ;) icon doesn't show up in toolbar on FF v.15 (which is prolly just my luck with technology and not a real issue) but the F9 key works.

Diese Bewertung wurde für eine vorherige Version des Add-ons (1.5.1-signed.1-signed) abgegeben. 

Toolbar button icon

You can add the toolbar button icon by right-clicking on any toolbar in the Firefox browser window, choose Customize, and then drag the Panic Button item to the desired location.