Product School - The global leader in product management training
The Product Folks - A volunteer-led community of product managers and makers
Product Managers Job Satisfaction - How to become a better product manager
Software Product Management Stack - Resources & tools to help you manage your software product
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
PM Starter Pack - Practical guide on how to get started in product management