It's just a coincidence, but it's an unfortunate one nonetheless. Reddit user carblos was in Tucson, near the site of the Arizona shooting, and noticed this billboard for Rush Limbaugh's radio show:

The billboard has apparently been there for quite some time, but Limbaugh's people might want to take it down now.

UPDATE: A spokesperson for Premier Networks, the company that syndicates Limbaugh's show, told Politico that the billboard was taken down on Monday, two days after the shooting.