Consider the BeBook Neo or Club readers. These will read many of the popular ebook formats.
Some libertarian-minded commenters here seem to think that Amazon is operating strictly within a "self-regulating" free market and ought to have the rights of private individuals and especially conservatives, who demand the freedom to ignore externalities. In fact Amazon actively engages in monopolistic practices and resists free markets. (I'll avoid the larger issue that Amazon depends deeply on government to ensure that markets it operates in function under controlled conditions, but resists acknowledging this and tries to avoid paying for the services it takes for granted, such as trademark, copyright, trade secret and patent protection--like many companies.)
I used to have an Amazon Kindle. They advertise low prices for electronic books. But those purchases are tied to an Amazon Kindle account, not to you. You cannot transfer a book you have read to someone else, as if it were a real book. The analogy between physical property and intellectual property breaks down. Amazon controls downstream copies of the electronic books you purchase from them. You pay $9.99 to Amazon for an ebook in the mistaken belief that you are saving money on the purchase of merchandise that purportedly behaves like physical property. In fact, that $9.99 helps Amazon stifle markets. If I sold you my Amazon Kindle with the books I purchased, and you re-registered the Kindle in your name, my books would vanish. It would be as if I sold you my bookshelf with books I purchased from Amazon, and Amazon removed the books once you claimed the bookshelf.
You could say that I agreed to whatever terms Amazon devised. Fine: not acknowledging that Amazon's monopolistic practices have nothing to do with free markets is ideology. And that is one reason why I am recommending the BeBook reader.