John Udell: The ultra-thin InfoCard
"Over the weekend I needed to log in to eBay from somebody else's machine. The browser was Firefox, but it would have been impolite to install Greasemonkey and Password Composer , or even to install a bookmarklet , so instead I just used the live version of the password generator that has dramatically streamlined my online life in recent months.
Astonishing. Three different implementations of a lightweight single-sign-on protocol; all interoperable; at least one guaranteed to be available to me on any Web-connected computer."