Tcldot is the Tcl package for Graphviz: the Graph Visualization Software. It makes the dot graph renderer available to Tcl scripts. See http://www.graphviz.org/cgi-bin/man?tcldot for the documentation.
Graphviz is available for Windows, Unix and MacOS X.
For an example, see XML Graph to canvas
If you need Tcldot for Windows, try this: [L1 ] (link broken ...)