Ask NH: Appointments(Booking) RoR SaaS platforms

I'm looking for an appointment(booking) webapp preferably developed on RoR which I can modify and use. Are there any such solutions... I couldn't find any suitable ones. Any help would be greatly appreciated.

EDIT: I should clarify that I'm looking for a solution which I can run and offer to my clients. Currently there is no such SaaS solution in my country.