Quote from this article on ask-leo.com: "Your username and password identify you to your email service, and your email address identifies you to the world."

If your application has anything related to sending the email then it is better to sign the user with an email option. If you want to refer to the person only, without having him to contact then you need to simply log him with username. Also, it would increase security for a user.

Registration: Username and password or email and password
I have a color sensor from the original lego mindstorms set. I have had a hard time finding any reliable specs on the thing, but I did find somebody who has reverse engineered it quite a bit here. The thing only has two connectors though. I am not very good at circuits, but I would like to hook this up to my arduino and read values from it. Does this appear possible? If so, do you have any idea which pins to use, or what kind of code I need?
