Powershell as Lisp
One of the interesting things about Lisp is the ability to use macros to effectively create your own language. Instead of using Lisp to solve your problem, write a language in which your problem can be solved and then solve it using your own mini-language.
When I heard of the new features in Powershell v2, the one that stood out for me was the ease with which you can create cmdlets using the Powershell scripting language rather than being forced to use C# or VB.NET.
One side effect of easing the ability to create cmdlets is that building your own mini-language will become very easy because you’ll have the whole .NET library at your disposal and you’ll also be able to utilise all other cmdlets and providers as well.