I have a client who is an instructor who teaches hourly classes. He wants to add a feature to his website that shows a weekly calander and his availability. Sounds easy enough so far ... He also wants his clients to be able to go on his site and see that Monday at 2 is available and sign up for that spot.

Any suggestions where I might start looking for something like this?

Maybe demonstrate to him

http://calendar.google.com/

and/or

http://calendar.yahoo.com/

Unfortunately, no APIs are available yet, but if he has an online account with Google or Yahoo, he could very well be interested in a link to his public calendar.

hello,
looks like our script - hitAppoint - can do the job

Thank you both for getting back with me. I will look into both of your suggestions. From what I know google and yahoo don't allow user input.