Rated 5 out of 5 stars

Yes like so many add-ons seemingly abandoned by their developers, I too wish it was maintained. Fortunately as with many add-on's editing install.rdf in the compressed xpi file allows you increment the max version for later versions of FF such as 3.03. I did find a ClearURL feature available in the current Konquefox 1.6.1 add-on at https://addons.mozilla.org/en-US/firefox/addon/2671 . Despite targeting Linux users this add-on works just fine in Windows XP with FF 3.03. The package provides four page navigation tool bar buttons and a fifth one for clearing the URL which is the only button I need and use with no issues at all.