There are many e-books available at Project Gutenberg—28.000, to be precise. They can be easily read on your computer, laptop or netbook using one of the many available software e-book readers, like yBook, or Mobypocket, or Microsoft Reader, or the Palm e-reader, the last three of which also work with other devices. They could also be read with Notepad or some other editor, as they are available as text.
However, I find most of these readers cumbersome in varying degrees, and I do not like to use many different applications when one will do. Notepad (or any other text editor) is perhaps the least convenient of all the choices. So I have started a few weeks ago a new project in ConnectedText, called "Books," in which I store e-books downloaded from the Gutenberg Website for reading. I download the text versions, and paste them into separate topics. I do minimal formatting (that is, I search for "_" and and replace it with "//" (for italics), and sometimes I transform the chapters into headings (===Chapter I=== etc.). I can thus browse by a Table of contents, if I want. Yellowish.css will do nicely as a style sheet for such books. More is not needed.
What I like most is that I can annotate these books as much or as little as I want to, using links to topics of my own. I can set bookmarks wherever I want, and, perhaps most importantly, the entire text of all books is automatically indexed by the program so that I can easily search for things whose place I have forgotten.
If I need to, I can integrate these books with my research. But if I don't want to, I can enjoy them on their own any time I want to. My Netbook, running ConnectedText, is not a Kindle device, but it is more convenient because it does not just serve as an e-book reader.
I can only recommend a personal wiki, like ConnectedText, for this purpose (as well).