The subscription ebook rental-service Oyster is heading to Android this morning, making its apps available in the Google Play store and for Kindle Fires after launching on the iPhone and iPad last year. Oyster has been called the "Netflix of ebooks" because of its subscription model: you pay it $9.95 per month, and you can borrow as many ebooks from its library as you'd like. You just have to give them all back once you end your subscription.

There aren't many companies taking this approach to ebooks yet, and the options out there — including on Oyster — are still limited. Oyster and Scribd are two of the bigger options, but they both only have two of the Big Four publishers on board. Both began with support from HarperCollins and they each recently added Simon & Schuster, filling in some of the major gaps. Still, that's a big selection of books missing, and — unlike a movie that can be watched in two or so hours — you have to be a pretty voracious reader to really take advantage of the all-you-can-eat subscription model.