I've been using macprovideo.com tutorials for photoshop and lightroom. I think they are great! and I refer to them often. I generally prefer them to books, but I also have a couple of books. The Macprovideo folks just released an iPhone app to run their tutorials - great idea! now I can refer to them when I'm not at my MacPro. I have no vested interest in macprovideo, just wanted to give them a strong endorsement for their great and innovative work.