NeetoCal builds a contact list automatically from your bookings. Whenever someone books a meeting with a new email address, a contact is created and kept up to date with their latest and upcoming meetings, so you always have each client's history ready before a call.
Open a contact to see their email, last meeting, total amount paid and number of bookings. The Timeline tab lists every booking along with internal notes, and the Notes tab holds a free-form note. My contacts shows your own clients, while All contacts covers the whole workspace for follow-ups. If a client mistyped their email, edit the contact and upcoming bookings use the corrected address.