This is not intended to start a pro-Apple/anti-Apple flame war. I am one of those people who likes both Apple and Google, which I realize is like supporting both the Israelis and the Palestinians, or liking both Art Garfunkel and Solomon Burke.
Anyway, like many people in math, and, I suspect other academic areas, I have hundreds of copies of books in djvu format, and it’s been my life dreams to carry a few of the classics with me at all times. Now, finally, there is a decent djvu reader for the iPad, called Stanza. Transferring the books is a little slow and it doesn’t support searches yet, but the formatting and readability are off the charts. For me, it’s game-changer for tablet computers.