I've been using Morning Coffee for a while. Love it. I have about 10 sites it brings up each day. I used to also have the weekly digi sales added in on their respective days, but I've taken those out for now until I have money to spend again. LOL
Other extensions I have:
IE Tab 2 - Lets me run IE from within Firefox for those occasions that I find something that doesn't work in Firefox.
DownThemAll - For downloading multiple files from one page simultaneously.
Fox Lingo - a translator. I haven't been using it long, but I have a couple of friends who only blog in their native language, so I can use that to right click on the page and get an instant (somewhat butchered) translation.
New Tab Homepage - Loads my homepage whenever I launch a new tab. (My homepage is iGoogle with a bunch of link boxes on it, so I use that for navigating.)
Personas - Just fun skins for the browser.
Session Manger - If my browser crashes, it remembers what I was doing. Also can save sets of pages to load on demand. For example, I have one set with various challenge sites around digiland that I bring up if I'm looking for inspiration. I have another set with all my CT forums. I also have it set up that when I close the last open copy of my browser, I have the option of having it bring back up the same pages next next time. Very helpful if I am working on something in the evening before bed that I want to continue in the morning.
I used to have the Google Toolbar installed as well, but it started causing some problems with alt text, which I like to use when skimming forums to peek at threads without opening them, so I've disabled it for now.