RemoteHQ - Real-time collaboration for distributed teams
Octopus.do - Build your website structure in real-time and rapidly share it to collaborate with your team or clients. Start prototyping websites or apps instantly.
Diagrams for Mac - A diagram editor for visualizing structures and processes
PowerMapper - Create visual HTML site maps and XML sitemaps for search engines of any web site quickly and easily.
Stately Viz - Visualize, simulate, and inspect your state machines
FlowMapp - FlowMapp is a UX planning tool for creating visual sitemaps and user flow.