Indispensable security add-on Rated 5 out of 5 stars
This add-on is probably the most important one I use. I need to use S/MIME in my daily work to send signed and encrypted emails to partners and clients. I use Thunderbird's S/MIME support, but I also wanted to use GMail's native web interface.
This add-on lets me pick the right tool for the job and I couldn't be happier with the results.
I reported a couple of bugs (interactions between GMail and Firefox 3) to the developers and they turned around fixes right away.