We have per minute solutions like that and you can setup something with us or use our site or have us write a program for you etc.
http://www.liveworldwide.net/start.htm
http://www.xlnttechnologies.com
We are also getting ready to launch a new site
http://www.realivecam.com
the idea is that you can schedule a live show promote it and charge a single ticket price to multiple viewers to access the show as oppossed to 1 on 1 per minute billing.