This happens to me on a regular basis, either I decide it is time to change a few passwords or sometimes I am asked to change a password, i.e. with the bank. Anyway, I always have a hard time trying to 'invent' a new password that is not easy for someone to guess, so I came up with a solution a couple of months ago. For me it is an easy option because of where I work, but may not work for everyone (however a supermarket car park can come in handy!).
Whenever I have to come up with a new password or change an existing one I just walk to the window of our shop, note down the rego of the vehicle parked closest to our shop and there you go, a totally random password that bears no relation to me, DH or our business. If you need more letters than the vehicle has I add part of the brand - Toy for Toyota, etc., or else add car, van or whatever. Saves a lot of hassle trying to dream up a suitably obscure password - I have used the name of our phone system, our old answerphone, the name of the hand lotion on my desk, all sorts of weird and wonderful odds and ends in the past, but the rego system is the best yet!