Case Modding 

Modifying your computer's case by removing the bland beige paint and painting it black with flames (or whatever you want!) adding extra fans and windows, cleaning up your inside wiring with plastic tubing, and then watercooling your CPU or videocard. Started out with Lan gaming fans who wanting to trick out thier rigs but its now spreading to the mainstream.
Adding Neons etc...

"wow you modded your case - cool case modding dude"

Case Modding by James Bryant December 22, 2004

case modding 

Just as hot-rodders create custom cars, PC modders modify their PCs into functional works of art. PC Modding can be aesthetic modifications like adding perspex windows, lights, ultraviolet cables, decals and other modifications.

"sweet case mod" or "I modded my case"

case modding by Knuckles10 May 9, 2005