One of the most valuable things I ever lost was the one sheet of paper with a list of all the words I misspell all the damned time. It moved from one bulletin board to the next as I changed jobs, and when my new job was mommy, I put it away somewhere, never to be seen again.
I'm sure it had murmured on it. Which I had to look up just now.
Maryn, decent speller who knows her limits
P.S. Ledbetter, IIRC there's a way to open your user-created spelling dictionary and edit it. I did it when I made a similar mistake to yours, adding both adrenalin and adrenaline. (Both of which just got green-lighted on Firefox's spellchecker.) So much for consistently using one, huh? Anyway, look into that for however you spelled florescent?