SmartDraw - Instead of starting with a blank screen, SmartDraw gives you the exact template you need.
draw.io - Online diagramming application
Diagram Ring - Diagram Ring is an all in one universal level of diagram editor for DFDs, pie charts, bar charts, flow charts, class diagrams and much more.
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.
GenMyModel - Industry Standards Compliance. Finally a tool which respects 100% of the UML 2. 5 standards to model your software, and BPMN 2 standards for your business process.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.