Office Ribbon UI with Visio Like Diagramming And Drawing
E-XD++ Diagram Control for C/C++, .NET, the professional Diagram.
E-XD++ Flow Chart Control for C, Visual C++, .NET, ASP.NET, with codes
E-XD++ UML Control for C/C++, C# and .NET, it can be used within Delph
Jade is a cross-platform diagram editor built on the Qt framework.
vsd2svg converts Visio VSD files into SVG