Why Let Users Create Passwords At All?
nxtpass.com
nxtpass.com
It's true that I'm a geek, but my girlfriend isn't (she's a gamer), yet she also has two computers she uses regularly. And she keeps threatening to get herself an ipad.
For that matter, my dad has a PC and an ipad at home (and he's neither geek nor gamer), and I think this sort of authentication system would irritate him into using a different site instead.
You can login with your password or just your username then click no-password login, an email is sent to your inbox, click the link, and your logged in.