Failory - Failory is a community visited by startup founders every day to read articles about entrepreneurship, interviews with failed and successful founders, insightful postmortems and our monthly reports.
Pramp for Product Managers - Practice product management mock interviews with other PMs
Reject Them Softly - Rejection letter inspirations from companies
The PM Interview - Practice PM Interview Questions (w/ timer).
Startup Graveyard - History shouldn't have to repeat itself
Apply to YC (Y Combinator) - Curated collection of resources for founders applying to YC.