RoundlyX - Roundup your spare change into digital assets!
UX Flow Wireframe Prototyping System - Create beautiful user flows prototypes for your next project
Micro SaaS Idea - Newsletter for anyone looking for profitable micro saas ideas
draw.io - Online diagramming application
Caply - With Caply you can collaborate and leave feedback directly on top of any website.
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.