Manufacturers have gotten away from the really black shingles. In fact, they've pretty much done away with any shingle that doesn't have at least three different color granules. The problem with the really black shingles, is they showed a lot of imperfections.
Plus, if roofers didn't work from about three different bundles at all times, there were real blending issues within the field of the roof. You could actually see different bundles because it was hard to get consistent color from bundle to bundle with the black.
So, with that being said, probably the "blackest" of the dimensional shingles today, would be the OC Oakridge.