Out last month, and I happened to stumble on it at Borders: Herbert McCabe's On Aquinas. McCabe died in 2001, and by all accounts was one of the most interesting modern interpreters of the man from Aquino. He was a Dominican, teaching at Fordham, and never published any books. His lectures survived, though, and this little collection is magnificent. If you've never read anything by or about Aquinas, this is the best introduction.
Here's just a small sample from his chapter on how Aquinas treats deliberative reasoning. He's quite chatty, by the way (almost breezy), in that typical English style:
One reason why I am deeply suspicious of the market economy, allegedly based on absolute freedom of choice, is that it seems to have no way of distinguishing between decisive choice and whim, and no analyis at all of adult human action. As I see it, adult decision is in important respects sacred; whim is not. [p. 93]True. One cannot help wondering just how many business models out there are in fact counting on whim, and how much damage that can cause a community.