I have two screens in a vertical configuration(23" primary, 17" secondary); a left-handed mouse, G11 keyboard, hacked together desktop PC(with side window currently removed for more airflow), and all in a 4' high area under my bunk bed. The perfect lair.
My two screens: Bottom is my main, top for IRC, TS3 and stats.
Also note the two red straps hanging my small lap-desk from the ceiling.

My top screen's got a custom screen mount, and is on a slider mounted to the ceiling:

and:
http://robbiethe1st.afraid.org/images/lair/20110425_001-small.jpegMy PC, with power for my top screen(right, purple/red wires); power for my keyboard/work light(MOLEX connector on left of PC), connectors for earphones, USB ports for my phone charger etc.

My lap desk, keyboard and mouse:
