Envoy - Visitor registration that's changing how guests are greeted in companies around the world.
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Teem - Cloud-based meeting room booking system
draw.io - Online diagramming application
Proxyclick - Connect with Confidence
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.