A handy set of isometric icons based on Visio's icons.
Stencil of additional Apple hardware and misc. networking components. Excellent for creating physical diagrams.
Stencils for QLogic Fibre Switches
Firewalls, VPNs, etc.
The following picture shows an OmniGraffle palette I put together for doing network diagrams. It may be useful for others.
The MacADSL team has designed a network stencil that can be used to draw networks in a comprehensive way with few colors in order to generate small image files to be published on the web.
Collection of hosts, clients and assorted support.
Falk Stern took a set of the basic Cisco router and switch icons for Visio and created a handy OmniGraffle stencil set out of them. Firewalls, routers, switches and even the ubiquitous internet cloud are all available.
This is an excellent stencil set of formal network symbols, for when the poofy internet cloud simply isn't enough. Oh wait — the poofy internet cloud is still there, hiding behind the moniker of "Network Cloud". That seems formal, maybe not black tie, but pretty formal.