I was checking out Digg.com and saw a story submitted about a Firefox extension, called FireGPG, that adds encryption to webmail. Lately I’ve gotten more into PGP/GPG encryption including sharing my public key here and allowing encryption on my Contact Me page.
FireGPG is a Firefox extension which brings an interface to crypt, decrypt, sign or verify the signature of a text in any web page, using GPG. It will support some webmails. Right now, only GMail is supported, some useful buttons are added in the interface of this webmail !