This question came from a blog reader and I thought it was important. As I've said, I'm still learning all about e-readers myself, and I can only go on my basic knowledge.
I started with Amazons Kindle for PC and enjoyed the use thus purchasing a Kindle 3G. The Kindle for PC allowed me to download books from many sources, but the Kindle 3G does not permit this. Amazon told me I could only down load e-books purchased thru Amazon. Do you know of another e-reader that will allow downloads from any source?
I answered below in bold. First, I know nothing about Kindle. I have two Kobo e-readers and the reason I bought them is because I was told I can download from various sources, including epub at public libraries, which is important to me because I love supporting libraries. So far, I've been happy. But if anyone has any knowledge about this, please feel free to comment. As I said, I'm still learning just like everyone else and if there's something I missed, I'd like to know.
This is why I bought two Kobo e-readers, the version with e-ink, and the Kobo Look Book, which is backlit.
The reason I bought Kobo is because I saw that I could download from more sources, including public libraries, than with Kindle. Below is the information link for Kobo, and on this page you will find a list of all the supported file formats (I'll list them below, too). And Kobo prices aren't that bad, compared to others. I actually found my Look Book on sale at my local CVS pharmacy for 49.99. About 100.00 cheaper than online. But that was a special sale, so I'm not sure how or when CVS does this. But I love them both.
From what I also hear, the best way to download anything you want is with an Apple iPad. But it's very costly, and the reason I didn't do it is because I only wanted a dedicated e-reader.
I will check around and if I come up with anything else, I'll let you know.
Kobo link: http://www.kobobooks.com/touch_tech
Here's what Kobo can download:
Books: EPUB, PDF and MOBI
Images: JPEG, GIF, PNG, BMP and TIFF
Text: TXT, HTML and RTF
Comic Books: CBZ and CBR