The single best third-party App on the iPhone (or the iPod Touch) showed up today, at least in the view of this avowed book geek. As a long-time fan and user of Amazon's Kindle (and now Kindle 2), and now an eager user of the new free Kindle iPhone app from Amazon, I heartily recommend people try this new App out, whether they own a Kindle or not.
Walter Mossberg describes all of this well in detail in this review today:
Called Kindle for iPhone, the app replicates the basic book-reading functions of the hardware Kindle device, and can be thought of as a complement to that device, which has more features. However, you don’t have to own a hardware Kindle to use this app. You can now choose instead to use your iPhone or iPod Touch as the reader for books from Kindle’s catalog."
He goes on to add:
It also synchronized to the furthest page I had read in that book on my Kindle. After reading for awhile on the iPhone, I performed that process in reverse, and my Kindle took me to the same spot where I had quit reading on the iPhone."
CNET has another review of the software worth reading with some additional details.
I'd add that Kindle books, at least for now, are generally less expensive to buy than their physical counterparts, partly due to Amazon subsidizing many titles. Most of them are available for $9.99, with many paperbacks available for far less.
In addition, since the iPhone is generally with me at all times, it's very convenient for a quick access to any book in my library I'd like to peruse at will.
With free samples of many books available for download on to an iPhone/iTouch, I'd recommend giving the free Kindle App a try.