Makerlog - Makerlog is the dead-simple task log that helps you stay productive and ship faster.
Product School - The global leader in product management training
WIP.co - Work in progress. We are a community of makers who help each other ship product.
The Product Folks - A volunteer-led community of product managers and makers
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
Intercom on Product Management - The ultimate resource for aspiring product managers