Now the Kindle has some serious competition and the prices for electronic book readers have dropped dramatically.
These days, more and more people are trading regular books for e-book readers like the Nook from Barnes & Noble.
Sales of e-book readers have almost doubled in the last year alone. But which ones work best?
Consumer Reports tested more than a dozen e-book readers, including the best-selling Kindle. Testers have also begun evaluating the new Kobo e-book reader from Borders, which is now liquidating its stores.
A key test is how easy the screen is to read.
"We're looking to see how clear and crisp the type is in different conditions," said Rich Fisco of Consumer Reports.
In one assessment, testers used lights to simulate outdoor sun. Readers with backlit screens had problems with glare. Those that didn't have a backlight were much more readable in bright light.
Another test sized up how quickly the pages turned, which can make a big difference.
In one side-by-side comparison, an e-book reader took twice as long to turn a page as the other.
Consumer Reports said there are three e-book readers worth considering: the Nook Simple Touch Reader, the Kindle Wi-Fi and the Kobo eReader Touch Edition.
They all cost about $140.
If color is a priority, Consumer Reports said the $250 Nook Color is your best choice. It offers rich color, which is great for people who read lots of magazines.
Consumer Reports says if you want a black-and-white e-book reader, you can save money by getting Amazon's Kindle Wi-Fi with special offers. It displays ads and costs $115, $25 in savings. You'll also get special offers, including discounts from amazon.com.