Traditionally, Modding has been about being lovely. Trust Microsoft to change tha... actually, forget about basic sarcasm. This is actually quite neat. In conjunction with Dr Dobb's Journal and something to do with CMP - I can't actually make sense of all the conjunctions - The Dobb's Challenge is basically a modding contest in Visual Studio. They provide a basic (yet actually quite fun in a quasi-Manic-Miner-esque fashion) Windows (and a different Windows Mobile game), which you can play to death. It's actually made by Grubby Games, who you may know from Professor FizzWizzle. And then you can mod it in Visual Studio and win prizes from a $10,000 prize fund. I doubt many of us will get further than playing the game, but for the brave souls who would do so, the FAQ is here and Visual Studio is over here.
In associated RPS news, your correspondent finds himself trying to learn C#. No, really.