From Rod Begbie's blog, a link to PwdHash, a browser extension that hashes a password against the domain name of the site at which you're going to use it, producing a unique password for each site. This means that you can remember and type in only one password at each site but the password that's actually used is different. Seems worthwhile and there are extensions for Firefox, IE6 and IE7 with a script for Opera.
Note that the opening page on PwdHash contains a link to the Firefox installer only. You need to go to the Stanford project website to get the installers for the other browsers.