These days I think long and hard before spending money on new software. There's so many different utilities that promise to make your computing experience a better one, a person could go broke buying them all! But I DID spring for the professional version of Roboform. And rarely does a day go by when I don't use it.
Roboform is an Internet Explorer add-on that watches for web sites that require you to log in. When you enter your user name and password, RoboForm records the information, and the next time it automatically logs you in without any effort on your part.
In order to keep your passwords secure, you can assign ONE password that is required before Roboform will log you in, or before displaying your complete list of passwords. Now there's a list you wouldn't want to lose!
You can also store your name, address, and/or credit card information, and when you're shopping, Roboform will enter this information in the web form for you upon request. You can spend a lot of money very quickly this way. Trust me, I know.
If you'd prefer to keep all these passwords in your head, you'll probably need some help, so take a look at "Cracking Password Usability... Exploiting human memory to create secure and memorable passwords" to help you create safe passwords, and then remember them all!
I've been using a program for the Palm Pilot called "Strip (Secure Tool for Recalling Important Passwords)". It stores all my passwords in an encrypted database, but is itself locked by a password. I only have to remember one password.
I just ran across an entry from InterAlia on this same topic. For more suggestions on utilities and methods to keep track of passwords, see the article cited there, How To Safely Store And Manage Passwords from Information Week.