I only have about 14 passwords I recycle...5 of them much more frequently than the others.
Of these 14, only 2 of them are of any noticeable length, and those 2 don't differ by much.
So keeping them all in my head isn't too difficult...the only problem comes when I try to access an account I have not used very many times.
I find that old wep keys are rather useful to tack onto passwords in a pinch.