Creating diagrams and graphs programmatically is one of passions. Below is a set of links you may find useful if you want to incorporate these techniques into your own applications. Where possible I’ve added licensing information.
Made by: ATT
License: Open Source CPL
Notes: GraphViz is a set of native (unmanaged) applications (dot.exe, neato.exe, etc.). Using them from a .NET language means calling an EXE with text input and text output.
License: Apache License 2.0
Microsoft Automatic Graph Layout
License: commercial (license is about $300)
Notes: I’ve used this in my projects – relatively easy to use and produces great results.
July 2009: there’s a limited time promotion code for purchasing a license for only $99
ILOG Diagram for .NET
Pajek - Program for Large Network Analysis
Data Visualization Components from Microsoft Research
Squarified Treemaps in XAML & C# using Microsoft Longhorn - http://www.codeproject.com/KB/recipes/treemaps.aspx
License: zlib/png license