Here is a list of all of my favorite apps for Firefox! all can be found in the firefox extentions directory

1- Deepest sender - A tool to post onto a Livejournal account

2- Quick Note- A note pad implemented into firefox, Awsome when trying to rember tid bits of information for short periods of time

3- Gmail composer - I dont have a pop 3 Mail account so this is cool. i can click on mail to links and this opens a gmail widow to send the mail to. (I think you need #4 or how else will it log in? but it does the job) you need gmail though.

4- gmail notifier - Lets you know when you get a message.