Flipboard!! I have been praising Flipboard and encouraging its use since I first got my iPad. I love it!
I love the way it keeps me organized and gets me reading my favorite blogs. I love the beautiful format! I love that it is flexible enough that I can add tons of different types of resources and it lets me keep up with them all. Mostly I love that it lets me follow my favorite Tweeters in a nice-looking format. Oh, and did I mention that it even let's me read it when I'm offline? (Although of course it can't pull any new content)
Another app that I would put in this category is called CoffeeTable. This app is every shopper's dream! CoffeeTable is filled with TONS of catalogs of every type imaginable! You can browse to your heart's content, and then click on and purchase anything you want!