Much to the delight of avid readers, Google Book Search is allowing the download of free copies of out-of-copyright books which one can read at leisure.
To find the out-of-copyright books, make a search after selecting the “Full view” radio button. From the results, click on the title of the result which would take you to the page dedicated to that book. The right side panel has the option of downloading, apart from other useful information about that particular book. The books get downloaded as PDF files. I must add here that the quality of scanning they have done looks very high indeed!
Read more about this at the Google Blog.