Embed the DotMac Kit, Make Money
That big server in the sky called .Mac just became a digital hub for your Cocoa application. At no cost to you, and no network programming, users of your application can enjoy all the benefits of the .Mac services, including global credentials, synchronized preferences across machines, and lightweight collaboration. As an added bonus, for each new .Mac subscription that your application generates, you collect $15. Not too shabby for giving your users a network-aware application that feels like home wherever they go. (Do I hear the rumblings of an open source project?)
My first Apple Developer Connection article, titled Using the .Mac SDK, shows you how easy it is to embed the DotMac Kit in your application. And it might be the easiest money you've ever made...