I don't know what big sites use App Engine but I personally use it for everything. Every weekend project, every work prototype, everything! I just love the fact

I don't know what big sites use App Engine but I personally use it for everything. Every weekend project, every work prototype, everything! I just love the fact that it's free to start with, and the idea that it's on Google's server sort of brings a level of confidence for up-time and scalability. Sure the fact that are some limitations (no IO and not many libraries) are a bit of a down-side, but the payoffs of using such a service instead of managing your own servers is really great. You're just able to crank a lot on the app code part without worrying at all about system administration work. The simplicity of the datastore is also a great benefit, and it scales like nothing out there.