Secure browser-based email

In my earlier post, no warrants needed to monitor web use, I mentioned that you could use PGP to encrypt the contents of your email messages. In the comments to that post someone pointed me to a site that you could use to do client based PGP email within a browser. I thought that was pretty cool, and deserved a post to point it out to others. This lead me to look for a similar solution for Gmail (my preferred email client), where I found this page on Gmail Encrypt. Gmail Encrypt is a Greasemonkey script that will add PGP to the gmail interface. Maybe this is something that should be added to the Better Gmail firefox extension.