"Smart" paper system
The Oxford EasyBook system based on Anoto marked paper and stroke-recording pens was excellent for meetings.
Including the margin markups to automatically generate to-dos, appointments and emails in Outlook.
As well as some really excellent searching and writing recognition/conversion to text. Sadly the software got EoL'd.
Onyx eInk Boox are useful, but the text conversion/search is not as good as the EasyBook software. (And until recently conversion was via China cloud.)