I downloaded Assassination Vacation by Sarah Vowell. Vowell is probably now most famous for being a voice in The Incredibles. Since grabbing it from iTunes I've listened to about 2 and a half hours of it.
In it Vowell essentially travels around America visiting historical sites related to Presidential assasinations. So far, about a third of the way into the audiobook, it's been really good. Funny and informative it's the sort of historical trainspotting that I recomend.