Reading about quantum mechanics, overview/amateur-level stuff. I'm (re-)reading books I may or may not have already read looking for a specific part I read once that I don't remember clearly enough. I want to include it in a couple of my essays. I've re-read two books, and I just bought another. I re-bought the two I'd already read, too, even though I think I still had them somewhere, because it was much easier than finding them in all my stacks. =P