[scdc]

right, so the email-only signup really just delays the step of creating a password. Is that better?

Would love to see usability commentary on these sites to see if/how they've decided to use one approach over another.

[sunchild]

It's better, in that you now at least know who to contact – someone who showed enough interest to provide an email address.

[SkyMarshal]

And sending passwords, even temp ones, through plaintext email is just bad practice, a solved problem, and totally unnecessary.