Although, I still wouldn't have an answer for you, someone else might.

http://www.cozi.com/

We used it for a long time scheduling pick ups and drop offs and events with the kids and grandkids and such. Not sure if it's right for a business environment but it does a lot of stuff. All platforms.

I will check it out.

A hair salon I frequent uses this software. It works really well for them, and they have Macs. I don't know if it would be appropriate for your friend.

1. you set appointment and choose stylist
2. It reminds you of appointment
3. It thanks you after you have completed your appointment

http://www.spa-booker.com

you might check the Freelancer's Union website. In addition to these kinds of program recommendations, they also send me 3-5 articles on how to better improve my self-employment. They referred me to both my invoicing service and my personal task-scheduler. (Todoist. Not functional for what your friend is doing but it allows me to schedule my work-projects throughout the day and track billable hours.)

https://www.freelancersunion.org/

Some of the articles they've sent recently:

How to Get Paid What You're Worth: https://www.freelancersunion.org/blog/2014/02/03/how-get-paid-what-youre-worth/
4 things no one teaches you in business school: https://www.freelancersunion.org/blog/2014/05/29/4-things-no-one-teaches-you-business-school/

I am a freelancer as well, so I'll look at!