Phillip Torrone of Make Magazine made the business of etching a gadget open source when he and Limor Fried founded Adafruit Industries.
His blog post How its Made: Laser Etching Powerbooks is still popular.
I love how it looks and still now sure if I'll ever make the leap.
But, if I ever get brave enough to tattoo my laptop, Engrave (discovered via wangjel), seems to be the place to go in Portland, Oregon.
According to their site, they can:
Engrave artwork or a picture onto your laptop, cellphone, ipood, or almost any surface imaginable.
Create a design or choose one of theirs and express yourself!