Coloured bar codes, a bad idea that refuses to dye (bad pun intended).
If you think color matching print jobs is a pain in the *ss now, try adding this to the mix. Besides, who really fills up a PDF417 or Data Matrix 2D bar code anyway? Right; I didn't think so.
I've seen coloured bar codes come and go over the years and quite frankly, I ain't impressed. A solution in search of a problem IMHO.