KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is locked with one master key or a key file. So you only have to remember one single master password or select the key file to unlock the whole database. The databases are encrypted using the best and most secure encryption algorithms currently known (AES and Twofish). For more information, see the features page.
I haven’t tried this yet. Using something like this requires a complete paradigm shift as to how one uses the web. I currently have a password system in my head that has worked for quite some time. It will be interesting how useful this is in real life use cases. Having the ability to have some other entity remember usernames and passwords can lead to very secure authentication. There will be no way to authenticate however if one does not have contact to this password database which could be a problem.