I have a dirty little secret: I have used the same password for my web site accounts for a very long time. Yahoo!, Google, Hotmail, Amazon, all of them — same password, unchanged for years. I've always known this was a bad idea, but I didn't want the trouble of creating unique passwords and changing them periodically.
That has changed. After hearing the description of PasswordMaker on the stackoverflow podcast, I decided to finally take action. Unlike a lot of other "password manager" applications, PasswordMaker doesn't require you to store your passwords anywhere or synchronize them between machines. Instead, it uses a hash algorithm to generate a unique password for each site, but you don't have to store anything anywhere. It can be used with any web browser, on any platform.
So now I'm changing all my passwords on all the web sites I use. I may even change them periodically.