Does anyone know how to draw queue network graphs that can be included within LaTeX documents?
See, e.g., the following examples at TeXample.net for the TikZ and PGF packages:
There are many ways to include drawings/graphs/images in your latex document.
The easiest way is just to draw the graph in your drawing program of choice, then export the graph to jpg or png (or eps if you're not using PDFlatex), then use the graphicx package ( \usepackage{graphicx} in your preamble), and include the graph in your document by using the code
\includegraphics[width=4in]{filename.jpg}
As indicated in other answers, there are several drawing languages that can be used with tex: metapost, tikz, and PGF are are powerful. There is also asymptote, another code based drawing language.
You could also use graphviz, which is excellent if your graph is large and you need graph something like network traffic. And dot2tex will turn your graphviz file into something latex can handle.