Rated 5 out of 5 stars
Works great from Firefox 4 to 7!
If you ever upgraded to Firefox 8 and lacking of the functionality in Firefox 8, See http://ayesh.me/content/how-get-im-feeling-lucky-search-firefox-addressbar
(this is how I fixed that)
Thank you for your review! I repackaged the add-on and uploaded it for review. If you're eager to upgrade, you should be able to find it on the "all versions" page.