Ask HN: Getting your username and password emailed to you?

When you register for site how do you feel about getting your username and password emailed to you?

For example: Register at site --> create username/password--> get welcome email with username and password displayed

We are debating if its more convenient for the user to have that info in an email or is it a security risk.

I personally prefer it in an email, espcially for a new site so if I forget I can look it up instead of reseting the password.

Your thoughts?