There are a ton of select Kindle bestsellers on Amazon, right now, all for the low price of FREE!! Anything from timeless classics to children's books, you're bound to find a nice freebie kindle book that strikes your fancy.
Don't have a Kindle? No worries, Amazon also offers a Kindle for your PC. (This is what I currently use)
Here are a few that you may be interested in:
Classics:
Fiction/Non-Fiction:
Home/Health/Self-Help/Food:
Spiritual:
Children's/Parenting: