Sure it's possible. Use a mentally computable one-way "hash" when creating your passwords, such that you (and only you) can generate a unique password based on

Sure it's possible. Use a mentally computable one-way "hash" when creating your passwords, such that you (and only you) can generate a unique password based on some attribute of the system you're creating the password for (name, domain name, etc). Of course that's also too much work for the average user. I think single sign-on systems with two factor authentication and other advanced security are a step in the right direction.