I would love to be able to use gpg or pgp withint webmails applications like gmail and yahoomail.
My needs would be :
- Possibility to verify a signed email
- Possibility so signed my outgoing emails
- Possibility to decrypt emails
- Possibility to encrypt emails
features should be implemented in that order. Key management from within the extension would be a plus. Any takers ?

Fred says :
The extension would read keys on my local disk - no need to store it on google's or anyone else's servers.
And having your PGP secret key stored into google's machines, and soon displayed on adsense advertisement ? No thanks.
The freeenigma extension for Firefox could help you with two of those four points, see www.freenigma.com. It seems like you can currently encrypt and decrypt with it, but signing/verifying is not enabled yet.