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 youd like. You just have to give them all back once you end your subscription. There arent many companies taking this approach to ebooks yet, and the options out there — including on Oyster — are still limited.