From Free Comic Book Day, I got Iron Man/Thor, and War of the Supermen.

Iron Man/Thor was a funny little oneshot. It reminds me of some old comics annuals I have, in that it's a short adventure that probably won't affect anything.

War of the Supermen was actually two stories, both prologues to a main series of the same title. It was very different in tone from Iron Man/Thor, which was much more light hearted, at least to me.