There are thousands of free ebooks available for reading. You can read them on your Kindle or Nook. If you don't have a tablet you can read them on your computer or smart phone using the compatible programs or apps. Here is a list of sites with free ebooks.
Open Library is a project of the Internet Archive and is an online catalog of over 20 million books. In addition, they have for download over 1.7 million public domain ebooks and some public libraries also list their ebooks with them.