In total I have three machines; Nim, Cel and Erf.

Nim Desktop machine. Athlon 1700, 512MB/PC2700, Matrox G550, SoundBlaster Live 5.1 digital, Maxtor 120GB
Cel General server-type machine. Celeron 333, 128MB/PC66, Intel i740, (not that it's ever used, being a headless server), Maxtor 30GB
Erf NAT-routing firewall. Pentium 75, 80MB/SIMM, cheap ISA graphics (also headless); 256MB compact flash (no harddisk)

All running Debian Linux (testing on the desktop and server, stable on router). The router and server on a custom 2.4.28 kernel, desktop on stock 2.6.10. (see my Linux kernel patches page for more information).

However, what is special are all the customisations, modifications, additions and so on I've made over the years, and will probably continue to make.

A collection of various items I've built to add to my ever-growing collection of computers.
The most notable thing anyone notices upon seeing my machine, is that it's blue. I don't mean I have a blue theme on the screen, I mean it's really blue.
I have a nice power controller for my computer, allowing me to turn on or off the monitor and speakers from a switch on the front of the actual machine. Here are details of this particular device.