I signed up for Readwise earlier this week after seeing it mentioned in Twitter somewhere. If you read a lot of ebooks on Kindle and make highlights, it’s a useful tool for recall and remembering what you read. Each day it sends you a brief digest with 5 highlighted passages from books you read in the past. I’m even getting reminders on highlights I made in books from 7 or 8 years ago. Already it’s made me consider going back and re-reading some things. It’s a neat service.