After recently browsing the Open Source Weblog, (randomly as I was checking out some of the links from the TAUW) I came across a post of theirs about a Firefox extension called Foxspose.
Simply put, cheers! Mac users out there will know the wonders of Expose in OSX, it's basically the same thing but for Firefox. At the click of a button, which I had trouble finding at first as it's down on the bottom left on the status bar instead of on the toolbar where I thought it'd be :/, it allows you to see all the open tabs in FF, handy if you've got loads and loads of tabs open, which I have done whilst researching on various things.
Basically I'm well impressed with this little (8k) extension, definitly worth getting for all Firefox users.