Generative Fast Fourier Transforms is a successful application of C++ template metaprogramming in the scientific computing. The metaprogramming makes benefit in two major aspects: library design that is naturally recursive, but resolved during compilation, and compile-time computations that add performance and flexibility to the code.
The original idea came to me in 2006 and is described in this online article. After a good feedback to the article and questions regarding source code, I started the open source project at SourceForge, where currently the only archives are stored. The source code is hosted on github.
Take a look at the GFFT home page.