GPGAuth is an authentication mechanism that allows you to use public/private encryption keys (GnuPG,PGP) to login into a website, there is no need to remember any password or username, GPG keys act as username and password verification is carried out in your browser, trust level for each website can be specified in GPGAuth options, like making sure that the User ID matching the domain has been signed by one of your trusted keys.
Keyloggers are easily defeated as you don’t have to type in anything, the server’s owner is given the public encryption key before hand making man in the middle attacks extremely difficult, with GPGAuth you won’t need to remember multiple passwords for every different site, it can be used as a single sign-on system, it is possible to create multiple User IDs from a solo GPG keypair, this allows for various online identities if needed.
The downside is that the website you are using must offer the possibility of using GPGAuth and it hasn’t exactly caught on. The browser addon is only available for the Chrome browser at the moment, the project uses the framework FireBreath to be cross compatible with Windows, Linux and Mac computers and all major browsers, there is no technical reason stopping it from being ported to other browsers addons in the future. If Chrome is your main browser you could use it in conjunction with WebPG, a GPG key management addon from the same author, otherwise you will need to have some kind of OpenPGP compatible software installed in your computer.