A Kindle is an example of an e-reader.
There is an unlimited number of ways to purchase eBooks online, but the easiest way is to go through the service or store offered by your e-reader.
These free eBooks are a great way to get familiar with your e-reader.
An e-reader can make a cool gift idea, especially for someone who reads quite often.
Mobipocket Reader - An outstanding little free application that gives you the ability to turn your BlackBerry into a great mini e-reader.
V.Reader - The V.Reader is an interactive e-reader.