Like these, for example.
Tab X: Puts an exit button on each tab instead of one at the end of the bar. Yay!
Options Menu: Links to Options of each of your Extensions in one menu.
Save Image In Folder: Yes, no more of those extra "Save Where?" options. Just save directly to a specific folder. Oh yeah.
Copy Plain Text: Oh the joy of not copying from Website to Notepad to Semagic anymore.
Gmail Manager: Say goodbye to the Gmail Notifier - this is way better.
Image Zoom: The only good feature of the AskJeeves toolbar expanded and by itself.
PDF Download: Now, like IE, you can see PDFs inside the browser instead of in the program.
And that's just a sampling of some of the things I've added on tonight.
Now all I need is an Extension Copier so I don't have to individually download all of these to the other computers I use. Alas, no one has invented that yet, I don't think.
EDIT: I've found a downside to FireFox. That is, I can't figure out what to make my homepage anymore. First, Google is part of the browser now in a handy little window, and I don't use it that much anyway. Also part of that drop down window is every other search site I use. LJ Frontpage is kinda useless and my Flist is a huge download for a homepage. Gmail Manager has all but eliminated my need to have it as a homepage. I officially no longer need a homepage. Sad, isn't it! This is what FireFox has done to me, I am a horrible wretch who has been eaten out of house and homepage.