I registered a 70-year-old real estate broker on Facebook and she’s thriving because she can easily stay in touch with others in the industry across a wide geographic area.
Facebook has a reputation as a time-waster so if you preface any mention of it to clients with how it is an extra service from you, I’m sure they’d appreciate your extra dedication to them!
In fact, I was watching a story on CNN just today about how some doctors keep in touch with patients on Facebook. The patients can easily ask simple questions and the doctors stay informed on their treatment progress. Much faster than making appointments, etc.