Update XPI Rated 5 out of 5 stars
Update XPI is available at http://mundogeek.net/update-xpi/ .
"Update XPI is an application to modify incompatible Firefox extensions to make them work with the new versions of Firefox."
It's an easy tool to bump the add-ons' maxVersion in the install.rdf up to 100.0. So most add-ons turn to get compatibility with FF5, FF6, FF7...
QuickNote is a very promising add-on. It enhances the value of Firefox.