Invision - Prototyping and collaboration for design teams
Savahapp - The all-in-one design sharing, collaboration, workflow and app prototyping platform
Atomic - The fastest way to design beautiful interactions
Pastel - Sticky note-based feedback collection tool for live websites
Pixelapse - Visual version control and collaboration workflow for open source and private design projects.
Visualtip - A service that allows designers and clients to annotate and collaborate on images in real time