If you are tired of remembering your passwords (or tired of always forgetting them), there are some very good solutions that will remember the passwords for you. The one I use is lastpass.com. It has extensions for all common browsers, which means that when I create any account, it offers to remember the login and password for me. When I come back to the site sometime later, lastpass offers to log me in automatically. Lastpass stands for "last password", as in "the last password you need to remember". If you need help installing or using it, leave a comment and I'll get a short screencast to show you how to do it.
In case you are not convinced you need to have different passwords, especially for the "unimportant" logins, read the excellent post "The thousand-dollar penalty for reusing passwords" by W. Leonhard
