I have recently started to use Dia to document network architecture of various systems, and have found this very easy (especially with the colour Cisco icons which I hear will be incorporated into version 0.95). Office networks were fine, but when I got to documenting a rack full of 1U servers I couldn't find any appropriate shapes - neither a Cray Supercomputer or a Mini VAX seemed appropriate - so I decided to make my own shapes.
Since you only see the front of a server when rack-mounted I decided to make these shapes two dimensional, which also meant they were easier to draw. I also created several different versions to differentiate between possible hardware vendors:
Dell Poweredge
HP Proliant DL360
Sunfire v120
Transtec 1001 (generic)Copy to your ~/.dia/ directory and extract. The shapes should be available next time you start Dia.
These shapes are distributed freely without restriction.