Add Account Limits based on unique visitors

The typical way host accounts is setup bandwidth limits but with unlimited bandwidth becoming the standard I am looking for something else to help manage the resources..

I would like to be able to limit customers on the number of Unique visitors they get.So for example, you could have three plans Plan A, B and C Plan A allows for 25,000 unique visitors in a month, if a customer goes over that they the account gets suspended just like if they went over the bandwidth and they need to make arragments with the hoster Plan B could allow 100,000 unique visitors and plan C could do 400,000. A unique visitor would be defined by different IPs within a 24 hour period