I'm just beginning to build a reading collection for my new iPad, but among the things I've gotten are online magazine subscriptions for the Newsstand app. Some I already read monthly, with the online subscription free because I have a home subscription. Others I had to buy online, the collection now including Consumer Reports, National Geographic, Bicycling, Road&Track, Popular Science, bon appetite.
Nice not to have to manage mountains of paper magazines, the whole collection is totally portable to a doctor's office waiting room, and I get immediate delivery the same moment I start a subscription. The one thing I don't get in virtual format are those annoying paper magazine inserts for offers I never use, that I always throw away.
Magazines work best for me on the iPad because even with the retina screen it's tiring to read off any screen for too long with my bifocals, PVD and cataracts, or even reading paper material for that matter. But I did download the complete works of William Shakespeare, as much for occasional reference as for reading pleasure.
I'm not a great book reader anymore, I might be downloading the Lord of the Rings trilogy, the works of Jane Austen, maybe some GB Shaw. All things I've read before, even multiple times, but contemporary authors don't interest me much.