This one works Rated 4 out of 5 stars
I accidentally got into fullscreen mode and tried to use esc to get out. It didn't work and I had to use the help forum to find out how to get out. So I wanted to change esc so I wouldn't have that problem again. (What program doesn't use esc to get out of fullscreen--other than firefox?)
This addon lets esc be the fullscreen toggle. The addon at http://mozilla.dorando.at/readme.html doesn't appear to work on firefox 3.