Rustoleum makes some textured paint, thats really strong and very durable. I painted my drive bay covers and buttons and such in a gray textured paint, it makes it a little more interesting to look at. Regular spray paint can scratch it lightly with your finger nail, most of my case is metalic black, i gotta be very careful with it, im scared to open and close too much, i got a small scratch on the top just setting a simple compu-nurse (small LCD temp monitor) which is just plastic with all round edges. It piled with 8 coats of metalic black paint and 4 coats of clear coat, i lightly sanded the clear coat down some too give it a duller shine.
check virtualhideout.net i saw quite a few cases using textured paint, i mean i throw by drive bays around all over the place and they don't have a knick on em. Hammered paint is another on ya might wanna look at, its an industral finish mixed with epoxy.
An old case pic
Pic with grill (eventully went without it)
Close up pic of the metalic paint
It looks alot more interesting with the drives in and all, i've done a couple more mods since then.