Software Product Management Stack - Resources & tools to help you manage your software product
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
The Product Management guide - A book on how to create and ship products that people love
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Product Management Exercises - A repository of product manager job interview exercises
Bigtent - BigTent is a web-based organization and communication portal for groups.