Startup Playbook - Written by Sam Altman & Illustrated by Gregory Koberger
Really Good Emails - A large collection of good product email design.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Good Email Copy - Email copy from great companies.
Founder Institute - Since 2009, the world’s fastest-growing startups have used the Founder Institute to raise funding, get into seed-accelerators, generate traction, and more.
Good Sales Emails - Best sales emails from great companies