Calculate password-safety as you type

I registered on EBay yesterday and when I was registering, I had to make up a password. When I entered my new password, EBay showed me how safe my password was while I typed it. That made me add another few characters, just to make sure I had a complete green bar for safety.

Then it hit me: that little bar actually helped me increase security. It's a small thingy, but security-implications are rather severe. I decided to write something like that for myself, that I'd like to share here with you. You'll find a small demo at

http://jetser.vhl.tudelft.nl/~guus/pwdmeter/

Currently, I check for variety of characters (numbers, upper- and lowercase, and symbols) and length of the password. Suggestions are very welcome, as I intend to use something like this in password-fields that I'm going to implement in the future.