Invision - Prototyping and collaboration for design teams
Anima App - Design, get feedback, convert to code, publish, iterate.
Red Pen - Red Pen lets you upload your design, share a short URL, and get live, annotated feedback super-fast.
Sketch Repo - Collection of resources for anyone who uses Sketch
Pastel - Sticky note-based feedback collection tool for live websites
Git Sketch Plugin - Version control for designers