I was a huge fan of Gen<X> from DevelopMentor. It was an unusual move for a training company to release a software product, and unfortunately it didn't do well sales wise, because they cancelled it.
What is Gen<X>? It's a generative programming tool. It lets you use code to generate code. An example of a generative programming task for .NET would be to create type-safe collection classes. The classes are pretty much just copy/paste, and you change around some data types on function signatures. Chris Sells already has a specialized tool for doing this, but now I expect that something using XCode .NET will probably be made from his excellent templates.
What is XCode .NET? It's a port of the Gen<X> code generation engine (XCode) to .NET; however, it uses JScript.NET instead of JScript internally. This has some great advantages: you get strong typing, good debugging, and access to the .NET CLR. It doesn't appear that there is any analogue to the Gen<X> GUI, or any VS.net integration yet; just the command line tool that does all the heavy lifting. I see potential future add-ons... :) Hopefully XCode .NET will inspire a nice community of "template code builders" like Gen <X> did! [The .NET Guy]
Oh hell ya...I'm all about this. I've been using XSL to generate code lately...