Firefox tweaks I can use

Personally, I use tips 9 and 10 from this guy's list of 28 Coolest Firefox About:Config Tricks.

Trick 9 is about how to handle JavaScript pop-ups, which differs ever so slightly from the normal method of pop-ups, I guess. Whatever. Ever since Firefox got the ability to open the list of tabs that were in the previous session, I was always a little ticked when I found out there was yet another Firefox window open that had an advertisement in it. Well, no more, Paco!

Trick 10 is useful for me because it enables spell check in all fields, not just the multi-line ones, and I am a horrible speller.