A cool Visio-like graph tool for under $300 that you can drop into C# code.
MSAGL is a .NET tool for graph layout and viewing. It was developed in Microsoft Research by Lev Nachmanson. MSAGL is built on the principle of the Sugiyama scheme; it produces so called layered, or hierarchical layouts. This kind of a layout naturally applies to graphs with some flow of information. The graph could represent a control flow graph of a program, a state machine, a C++ class hierarchy, etc.