productboard - Beautiful and powerful product management.
ProductPlan - Cloud-based product roadmap software solution
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Product HQ - Product HQ is product management software to manage all aspects of product management.
Roadmap - Collision avoidance for projects and people
ProductFlare - Kickass roadmaps & product management software