Conditional configuration: How to detect if I'm local or online?

[Mark!]

I want to provide different configurations for local and offline. At the moment, every time I upload my stuff to the web server, I must make sure that I don't mess up with the different config files. One for local development, and one for online.I slightly remember a couple of years ago, a code snippet distinguished somehow automatically between online and local development.Is there a safe way to detect that?