A video of a presentation to the Freebase User Group with some good stuff on data mining, visualisation (and some bonus API action) via the Freebase blog.
If you haven't seen it before, Freebase is 'an open database of the world's information', 'free for anyone to query, contribute to, built applications on top of, or integrate into their websites'. Check out this sample entry on the early feminist (and Londoner) Mary Wollstonecraft. The Freebase blog is generally worth a look, whether you're interested in Freebase or just thinking about APIs and data mashups.