The power of metaprogramming

The ability to create functions at runtime, using metafunction techniques, can save programmers hours of coding and increase the efficiency of their applications. However, creating the necessary metafunctions is not for the casual programmer.

http://www.artima.com/cppsource/metafunctions.html

As you can see by the book excerpt, metaprogramming can be extremely powerful. [b]What functions are conducive to metaprogramming? In what way have you used metaprogramming techniques?[/b]