Passwords and password memorisation simply stated is a chore and many people reuse the same password for multiple services to avoid having to remember them. Enter password managers. I am not going to review them in this post, rather point you to a lifehacker article that does a decent job of reviewing them.

The summary is to use one that meets you needs rather than re-use the same password. If you go the next step, you can then store your password file (which should already be encrypted) on an internet facing service such as the Otago Syncplicity service where it will be available to you from anywhere on the internet.