Online Scheduling Tool

I'm looking for recommendations for a (preferably free) online scheduling tool which can be accessed by a number of people.

I would like to be able to send schedules to various trainers. It would be good if the schedule could be colour coded by course and by trainer and could support some reporting. Any suggestions?

Google Calendar with a shared Calendar

What burmo said.

You also get SMS reminders (free) and email reminders with Google Calendar.

Thanks guys - I had a look at this last night and it does look like it will suit our needs. I appreciate your help.

I did a bit more work on Google calendar last night and now I'm not sure that it will suit our needs. We would need to have a calendar for each client and then we would also want to be able to see the availability of people to slot in for each session. If we do the calendar by client, we won't be able to send the schedule to the trainers as there will be different trainers with each client. If we do the schedule by trainer, the client info will be muddled. Is there any way of doing this without setting up a different schedule for each client and each trainer?