Using a hash of what you are hashing as a salt?

Question

Say a user registers for your site, you hash the password they have chosen then use that hash as a salt and rehash their password with that salt.

Example:

Answer 1

Instead of hashing two times you should use the username as salt for the function:

String hash = MD5(username + password)

You should also consider using a different function as md5 is considered broken MD5