Stack Style Tabs is an extension that changes Firefox's Ctrl Tab functionality to something similar to Windows' Alt Tab task switcher. When you press Ctrl Tab a menu with the titles (and icons) of your open tabs (nicely uncramped compared to a full tab bar) pops up and remains visible until you release the keys. Pressing Tab with Ctrl held down lets you select the tab you want and releasing Ctrl will switch to that tab. Excellent!