Works in Firefox 5.0 Rated 5 out of 5 stars

Just hacked the em:maxVersion in install.rdf in the .xpi (zip) file, added the button back and it's working perfectly.
Agree with the other reviewers: should be built in, icon style should match, https -> http, keyboard shortcut, (but don't add www - see no-www.org).

This review is for a previous version of the add-on (1.5.7.1-signed.1-signed).