I’ve recently added two of my e books, Canon T3i Experience and Nikon D7000 Experience to the e book super-site Smashwords. If you purchase them from that site, you have access to a variety of e book formats so that you can read the guides on all of your devices. You can download copies of any or all of the formats for one price. There is PDF format for general computer reading and printing or for transferring to the iPad, MOBI format for Kindle, ePUB format which is becoming the industry standard for a variety of e-readers including the Nook and Sony Reader, or else LRF or PDB for Sony or Palm.
Click here to see and purchase Nikon D7000 Experience on Smashwords, or
Click here to see and purchase Canon T3i Experience on Smashwords.
These two e books (as well as all my other e-books) are now also available at the Apple iBooks store. You can have a look at all of my available books on iBooks / iTunes here .