Email Marketing: A Beginner's Guide - Master email marketing with these 3 short ebooks from Drip.
GrowthList - A crowd-sourced list of growth hacks
HubSpot Free Email Marketing - Powerful drag and drop email marketing in the HubSpot CRM
GrowthHackers Projects - Growth collaboration software for teams 📈
Quokka (formerly Kryptowire) - The gold standard in SAST, MAST, IAST, and more!
Marketing Examples - A gallery of real world marketing case studies. Updated every day.