I’ve seen this all over the web today. Amazon has just opened a new program called Kindle MatchBook. If you buy certain books, you can get the e-book for a greatly reduced price (from $2.99 down to $0). More than that, the deal applies to any books you’ve ever bought from Amazon in the past, provided that they are on the list. Just go the above link, and check; Amazon knows what you’ve purchased. (Big Brother is watching you, and he has Really Good Deals!)
Amazon listed three books for me, only one of which I wanted to get as an e-book; but although the number of books in the program is small at present, it’s expected to increase greatly over time. I expect to check back every now and then.