password theft and you Terms and Conditions
 

here's how one company change their terms and conditions to deal with password sharing:

I will not sell or give out my user name and password to anyone. Our secure server checks your IP address when you log-in and if it sees you coming from too many IP addresses you will be denied access. If my user name and password is used to access any of the COLT websites from several different IP addresses, I agree to let COLT Studio charge my credit card a membership fee for each log-in. COLT Studio reserves the right to terminate any account that the username and password have either been sold or given away without prior notification.

Your sig is obscene, it made me go blind :/

Try to enforce this and you billing will be swamped with chargebacks. Even in court you would loose because you would have to proove that it was the surfers fault the password got published. There are many options on how this could be public. Hacker attack on the site, guessed password etc.

I second that.

Also, what about dial-up users, or people who use different computers regularly?

yes, you would get swamped with charge backs and billing fines for having too high a percentage of chargebacks. The best way to do it would be to simply shut them down and make them sign up again if they start sharing

If I remember correctly, Colt Studios seems to be highly sue-happy. I think I remember seeing a lawsuit in Florida against a hosting provider and the hosting provider's bandwidth provider for one of the hosting provider's customer's copyright infringing activities.

Don't take this as fact... I think I remember seeing it though.

I guess that doesn't really apply in this case but it does show how they think.