Looking for an availabiity scheduling script

[TalkVirginia]

I image everyone has seen the scheduling tab when setting up an appointment in MS Outlook. On the left side it shows a list of attendees. On the right, it shows days of the week from 8am to 5pm in 1 hour blocks of time. It shows the availability for each desired attendee to see when they have a free block of time. I'm looking for something similar to this in a php web-based application. I would like to try to port this type of functionality into a VB addon. I have a group of members that would like to schedule online meetings and know when members of the forum are available. Would anyone know where I could find something like this as examples of doing this in php with bar graphing?

Thanks,
Jim