well, I'm probably misusing the word "billboard" - they're small, A3 sized cardboard boards on lamp posts and what have you, and every day a small army of workers sticks up a different paper headline, three or four headlines per major newspaper. They're definitely billboards in the classic sense of boards to which bills are stuck, although not the giant ones with glitzy artwork. We also have those :>. You'd be surprised at how much linguistic interest the big ones do offer, too - anywhere you have a short, punchy idea to express leads inevitably to word play. The De Beers diamond ones out by Canal Walk are particularly fun.