Product School - The global leader in product management training
The Product Folks - A volunteer-led community of product managers and makers
know/how Product Managers - A weekly newsletter with 5 practical tweet-length PM tips
The Product Management guide - A book on how to create and ship products that people love
Better Product Manager - Experience the life of a PM through these tests
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.