I made a post a week or so ago about how to make a viral site, and I wanted to add to my list of TODOs.

1. Make the registration process easy
   1. Either require as little information as possible or use a social framework like Facebook Platform or OpenSocial

This great blog post describes a usability study that looks at the registration frequency for different types of required information such as email, password, address, etc. Go take a look if you’re designing a registration process.

Update: more here.