I do something like this:
1. Take a password only known to me.
2. Use it on every site, but...
3. Hash it with the domain of the site.
Say I'm using the password, "password".
For axiomaudio.com I would take the string, "password+axiomaudio.com", and run it through a hashing algorithm.
I have the tools on my computer to do my own hashing, but you can use a site like this: http://www.sha1-online.com/
So "password+axiomaudio.com" hashed with MD5 becomes: 287398526177c51d26bfc383fb4a27f8
You can use some rule to shorten the password. Like only use the last 12 characters. To make it a little stronger, capitalize the last letter, and change the second number to it's "shifted" version.
So the final password becomes: c3*3fb4a27F8
Using those rules, you can always figure out what your password for a site should be, and it will be unique for each domain.