Here in Delaware, at least in the urban areas, there's a great deal of glass on the roads. Also, debris of all types, sand and gravel and every imaginable piece of scrap metal known to man. But I've had good luck with emailing the DOT and asking them to sweep certain sections that are particularly bad.

Oh, and did I mention how much I love my Panaracer Pasela tires in the urban jungle? *knocks on wood*