productboard - Beautiful and powerful product management.

Product School - The global leader in product management training

Aha - Aha! is the new way to create visual product roadmaps. Web-based product management tools and roadmapping software for agile product managers.

Intercom on Starting Up - A book about growing a startup

ProdPad - ProdPad helps your team gather ideas, surface the best ones and turn them into product specs, and then put it all on a product roadmap.

Prowess - The simplest way to collect and leverage product feedback