I tend to use one for the bank and one for everything else. My main password is a word of over six characters that I can easily remember. What infuriates me is those unnecessarily "super secure" sites which insist that the password is made up of a combination of letters and numbers which you have no hope of remembering - 'cos you are not supposed to write them down! I tend not to bother with such sites, nor the ones which cancel your password every three months and insist you invent another one.
I have now even managed to crack the problem of logging onto PPRuNe every 24 hours on my home machine. I won't need to log on again until 2010 unless I log off or clear out my cookie folder!
(rant over)
P.P.