Remember this? http://joyreactor.com/post/1733746 

There're more!
Rubber residue from tire mold:
,laser,gif,animated pictures
Patina from bronze eagle:
,laser,gif,animated pictures
Paint from a car:
,laser,gif,animated pictures
Dirt from marble:
,laser,gif,animated pictures
Dirt from stainless steel:
,laser,gif,animated pictures
Rubber from steel:
Ink from an anilox roller:
,laser,gif,animated pictures
Residue from titanium nitride-coated molds:
,laser,gif,animated pictures
Pencil from paper:
,laser,gif,animated pictures