The way I do it, so that they're easy to remember for me, but hard to figure out, is;
I have 3 bases which may or may not be real words.
Then I have three strings of numbers which have significance to me but not obvious (not even close to my birthday or license plate).
I then take those and mix them up for each new account I need secured. There are more common ones which I use for things in which I need less security. And rarer/longer password combos which might actually be cracked (like MMO accounts).
So if I forget, I first ask myself the security level, which narrows it down, then usually remember the letter string associated with the account, then its only 3 choices on the number string. So I almost never forget my passwords, yet I have 9 standard + ~3 bonus varying in complexity all the way up to 12 characters.
Yes, I'm quite pleased with myself
