Here's a Visio diagram of my current infrastructure. You're reading this webpage right now from it. It's admittedly not very good as far as Visio diagrams go, which is why I'm calling it a work in progress.
Rack.vsd (217.50 kb)
If you don't have Visio installed, you can get a free viewer off the web.
Edit: Contributor Sam Powers converted it to PDF for me here:
MOPCIAC.pdf (145.61 kb)