If you work in a Visual Studio solution that contains lots of projects (in my case, about 90), you occasionally need to check your project dependencies: in a multi-layered architecture, a project may only reference projects of certain layers, but not of others.
A quick search gave me 3 tools that visualize VS solution dependencies
All of them make use of the GraphViz library, so their output looks similar.
I tested with a couple of .sln files dating back from VS2003 up to the current VS2010. These solution files are from C# software projects that I created or that I was working on, so your experience may be different.
depcharter
After installation depcharter, which also includes GraphViz, depcharter can be added to the context menu of .sln files by adding a .reg file to the registry.
However, I never accomplished to generate a chart using depcharter. It crashes on web site projects, and otherwise ends with the messages “No dependencies, nothing to do” or “Error generation diagram”.
DependencyViewer
DependencyViewer is a WPF application that opens a selected solution file, allows the user to select/deselect the projects to be included in the chart, and select an output filename. After generating the graph, the resulting .png file is automatically opened in the default viewer.
DependencyViewer crashes on some solution (my guess is either web site projects and/or spaces in paths), but successfully generates png charts:

Dependency Visualizer
Dependency Visualizer installs itself as context menu on .sln files, and provides a separate configuration application to adjust some settings, such as inclusion of referenced assemblies and .Net libraries in the chart.
Upon right-click, Visualize Dependencies, it generates a .png and a .svg chart in a newly created Dependencies subdirectory of the solution’s directory.
Unfortunately it only supports Visual Studio 2005 and 2008 solution files.

Conclusion
Not all visualizers support all kinds of projects in solution files. (Disclaimer: any program error or crash may be caused by my handling of the applications)
Generally speaking, charts generated GraphViz are quite huge: they range from 500Â pixels wide for simple solutions (10 projects), up to 12.000 pixels wide for a solution containing 90 projects.
