CS183B - Startup Class - Stanford class taught by Sam Altman & guest speakers
Startup Playbook by Hatch Quarter - A guide to building your startup
Classroomies - Watch Stanford CS & Startup lectures together
On Slack by Standuply - The most extensive book on using Slack to the utmost
Frond - A better way to build community online
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.