Awesome! (updated with INSTALL TIP) Rated 5 out of 5 stars
Let me be the fourth in a row to say "Great job, does exactly what I was looking for." I've been using a Greasemonkey script to do a very similar function, but it's not as good as this.
And let me also be the third to request a keyboard shortcut. I'd also like the ability to disable the status bar icon.
UPDATE: Nathan hooked us up with a keyboard shortcut and option to disable the status bar icon.
INSTALL TIP: If you're getting the dreaded "Invalid file hash (possible download corruption) -261" error message, it's due to a known bug in FF3. 2 work-arounds: 1) enable 3rd party cookies or 2) get this add-on at softpedia