PlayStation Now is a pretty cool idea. 100's of PS3 games that you can stream to play over your PS4. While it is not true backwards compatibility it is pretty close, and if you never actually owned the games you could just play them from here. Downside is that it was super expensive comparatively to actually play the games. But that will soon no longer be a problem. Starting on 01/13/2015 you can subscribe to the service for $19.99 one month at a time or 3 months for $44.99 ($15.00 / month) for unlimited play of the entire catalog.