FlowMapp - FlowMapp is a UX planning tool for creating visual sitemaps and user flow.
RemoteHQ - Real-time collaboration for distributed teams
A1 Sitemap Generator - A1 Sitemap Generator has been in active development and sold since 2005.
Terrastruct - A diagramming tool for software architecture
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