After purchasing premium, members should be able to play live games on the site with a friend in the room, off of the same computer. I know the quick answer would be to tell a friend to go freemium, and play your friends this way. However, this would involve constant logging in and out of CC with different usernames and passwords, making it look like you would be a multi using the same IP address.
While playing Live Games, your score/rank will not be affected.
How this will benefit the site and/or other comments:
This will bring new people to the site, plain and simple. Countless times as a member of CC, a friend has come over to my house, and they see me totally addicted to CC. I tell them all about it, they become interested, but they can't play. They watch me play it. I suggest that they start a fremium account, but they never do. This could also work within the confines of the referral program, there could be a question such as: "Were you referred to CC by an active user?"