NYPL Biblion: The New York Public Library has a stunning new app that lets you see a ton of essays, pictures, people, etc and information about the 1939-40 World's Fair. It's like a time traveling machine that brings you back to that era. The app is great too (though occasionally over the top), and easy to navigate, with stacks grouped together and galleries that are easily navigable. Free.

The Final Hours of Portal 2: It's a 15,000 word, 13 chapter account of what it took to make Portal 2. Keighley, who has done this before with Half-Life, specifically wanted to use the iPad as his medium this time so he could include photos and videos to better illustrate his words. So imagine a huge feature in a magazine but more interactive and more absorbing. $2.

SnagFilm: It's a streaming video app that specializes in documentaries. Which sounds incredibly boring! But when you're given a platter of docs, you start realizing how much cool shit there is to learn about. And sure you might get your doc fill from Netflix or basic cable but SnagFilm is completely free (sponsored by the rich suits at Goldman Sachs) and comes with a pretty good selection. Free

Dark Horse Comics: Dark Horse. It's the largest independent comic book publisher in these here United States, and its stable of titles ranges from Hellboy to The Guild to Conan to heart-warming child-written internet sensation Axe Cop. And now it's on your iPad. Free.