Ah, good thing it can import XML Rated 4 out of 5 stars

http://techpatterns.com/downloads/firefox/useragentswitcher.xml
So now I just need to find a list of just the major ones:

Safari, IE, Firefox, Opera

XP, Vista, Leapord, Hardy, Sulfur

Once I get it configured properly it looks like it'll really come in handy.. I'm used to just using about:config for all this ;)

This review is for a previous version of the add-on (0.6.11).