FireGPG
I must have been living under a rock since March 10th, 2007. That was the date of the first release of FireGPG. The name merges Firefox, the best browser in history, with GnuPG, which is the Gnu Privacy Guard package. FireGPG is a firefox plugin which brings a user friendly interface for GnuPG to Firefox.
GnuPG is a free implementation of the OpenPGP standard defined in RFC 4880. PGP stands for “Pretty Good Privacy” which humbly states the obvious. You can encrypt text using public and private key pairs and exchange this data with people you have public keys for. This ensures messages come from intended senders and are only opened by intended recipients. It’s good stuff.
FireGPG actually even has a tie in to Gmail which is a service I use. It integrates seamlessly with the compose message interface, providing buttons to clear sign a message or encrypt, sign and send. It is really slick.

