Canny - Canny helps you collect and organize feature requests to better understand customer needs and prioritize your roadmap.
UX Flow Wireframe Prototyping System - Create beautiful user flows prototypes for your next project
Feedback Fish - Collect feedback & make your customers happy.
draw.io - Online diagramming application
Customer Feedback Portal - Ask customers what you should build next
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.