I am having to brush up on my Visio and be able to put together a nice looking network diagram. I will document the resources I am using as I find them in the hopes it will help me later or help someone else going through the same.
Visio Cafe - Source for Sharable Visio Stencils. (collections of shapes for various manfacturers products)
Network Diagram Templates from Microsoft
VisGuy - Visio Guy has a whole website all about Visio and the cool stuff you can do with it.
Microsoft Visio Team Blog - get the latest insights into what features are being added to Visio 2010