...or any reasonable online booking system! The examples I give have APIs and a team interested in integrations. Both do to google and outlook, but if it was with an online booking system you would have a flawless flow of appointment data into the workshop module, instead of having to manually enter every online booking in, saving heaps of time and reducing errors.
Realise this is big dev but putting it out there, and you could always look at your own online booking system :)
Scott