Dual-head
As I write this, I'm not only using a second monitor connected to my Ubuntu Linux 6.10 laptop, but also plugged it in after I booted, have different resolutions on my built-in LCD vs. the external LCD, and ran one command to go from single to dual-head without restarting Xorg.
My hardware is a Lenovo/IBM Thinkpad T42 with an ATI RV350 and native resolution of 1400x1050.
[tags]dual head, ibm, lenovo, fglrx, ati, xorg[/tags]