One of my favorite columnists, David Brooks of the New York Times, has published his list of Sidney Award winners for the best magazine articles of 2009. In Brooks' words, these awards are meant to recognize, "celebrate (and provide online links to) long-form articles that have narrative drive and social impact." (Pace yourself. There are two parts, each with several lengthy essays, all excellent.)
Dig in for some serious nourishment of history, current events, politics and all sorts of other sustenance that will beef up your speechwriting muscle, not to mention making you a more deeply-informed citizen of the world.
Any other resources like these that you find especially valuable in building your repertoire of speechwriting skills?