I happened upon a brief discussion recently on another site about C# runtime compilation recently while searching for something else and thought the idea was interesting. Have
something I used it for was for allowing C# and VB code to bu run by the user ad-hoc. They could type in a line of code (or a couple lines) and it would be compiled, loaded into an app domain, and executed, and then unloaded. This probably isnt the best example of its usage, but an example of it none-the-less