The Product Manifesto - Product Managers face the biggest challenges of our day, which is why our community needs a common set of product principles.
Product School - The global leader in product management training
Intercom on Product Management - The ultimate resource for aspiring product managers
Intercom on Starting Up - A book about growing a startup
Prowess - The simplest way to collect and leverage product feedback
Product Management Exercises - A repository of product manager job interview exercises