Mark Lautmann has a great site full of custom OpenOffice.org shapes in Draw.
From his site:
"You love OpenOffice, but you still use Visio to make drawings. Why? Because none of the shapes you need are easily available. Until now. Custom OO Shapes is a repository of custom shapes you can use with OpenOffice Draw."
Mark has many categories. One is basic network shapes such as a tape drive, multiplexer, bridge, hub, modem, printer, comm link, server tower, server blade, desktop PC, radio tower, cell phone, router, rack-mount unit, IP phone, laptop, and wireless access point.