Amazon now has Kindle software for PCs available for free (and a MAC version soon). Learn more about how this software works at NewsFactor Network.
If you don’t want to purchase Kindle books, you can find some available for free. Amazon offers thousands of free books at the Kindle Store.
The iReaderReview Blog has more information on how you can get many more free books in the Kindle format.
I’ve found a few others places for Kindle free books which you might find useful:
Amazon’s best selling free books (great to see a few classics make it onto that list)
http://www.amazon.com/gp/search?node=154606011&p_36=0-0&redirect=true&tag=discounter-20
Masses of public domain books formatted for Kindle
http://feedbooks.com/
User tweaked ebooks for Kindle
http://www.mobileread.com/forums/ebooks.php?forumid=128
Smashwords – an indy pubisher
http://www.smashwords.com/books/category/1/newest/0/free/any?ref=me