UPDATE: I contacted Amazon about this rumor, and their response was that they have not announced anything about a subscription based service at this time.
There is a rumor going around that Amazon is in talks with publishers to create a subscription based service for the Kindle. This would most likely mean that for a monthly fee, you could download and read an unlimited number of books. Here's the article if you're interested: Amazon In Talks To Launch Digital Book Library: WSJ.
Of course, the big publishers are probably going to scoff at this. They will probably see it as a money loser and something that could devalue books. This is rubbish thinking though. Look at Netflix, Zune, and Spotify. They have subscriptions for movies and music, yet I don't see it hurting their value. DVDs, MP3s, and CDs still have the same value.
That's why self-published authors need to jump on this bandwagon now. Better to be on in the beginning of a major change than the end. This is a great way for us to get exposure, and get our stuff read because it takes the risk out of it for the reader. I'm not sure how Amazon will address royalties with a service like this, but I do know I want my stuff to be a part of it. That's why I've contacted Amazon to let them know I'm more than willing to do it.
Would you be interested in making your eBooks available for a subscription service? Then let Amazon know. Contact them from the KDP contact page, and tell them they don't need the big publishers to agree to this because they have a multitude of self-published authors who are ready to do it now!