I hate passwords. I mean, I don't mind having really important ones be made-up and memorized but what about all those e-commerce and community sites that want me to create accounts? I end up using the same password at all of them and then I feel stupid knowing that one SQL Server exploit or disgruntled admin could cost me my whole identity.
Then just hit return and copy your new password so you can paste it into whatever site you're registering at. It'll be different for every site, and undiscoverable by anyone who doesn't know your master password but you can always retrieve it by simply using this form again.
(Note that all this is done by your browser running the program that's in the source of this page; nothing is passed back to my server. You can make your own local copy of this page, use it off-line, &c.)
Here's a bookmarklet version, which is pretty neat and works now on both http and https sites.
Infoworld's Jon Udell has posted a cool movie showing how the generator works in practice.
Here's someone else's version that uses base64 encoding instead of hex to fit more chaos into 8 characters.
And here's a version of mine that uses SHA-1 instead of MD5 and base64 instead of hex.
Zsolt Molnár has made a Google Gadget version.