I'm curious to know why a sign up on the main page is a bad, bad idea. I am developing something myself and figured that having a quick sign up form on the main page would ease the sign up process instead of click on "Sign Up", go to another page, and then fill in the form. On the main page, if you like the site, it's a quick decision to just sign up then n there. My site requires a user to sign up before he/she can interact with other users (privacy concerns etc). So it's more important to me that the sign up is an easy process.
Yes/No? What am I missing?