Blake Commagere: "As you’re figuring out what you’re going to do with your apps, your database server is always going to be your constraint. We leverage memcache, we leverage Facebook’s caching. We chose Ruby on Rails because we could build our apps much faster with limited resources. Focus on your database and make sure it’s solid. We use MySQL on a machine with 32GB of RAM. Our app servers are cheap, but they do great. You don’t need 100 app servers to serve millions of users." Zombies has ~2.7M users right now? Seems like Rails is holding up just fine :)