Hi Sarah -
In v3.0, it is still not possible to create an Appointment type activity with Workflow.  What you could do is create a Task for the user notifying them that they should create the Appointment Activity.  At least there is some kind of notification to the user that there is an action they need to take.
 
Using workflow to create emails actually sends the email to the person identified in the workflow.  One thing you could do however is create the workflow using the Manual rule.  So at least the email wouldn't be sent until the workflow is invoked by the user.

Let me know if you have any further questions.

Amy Mayer

Inetium