CplusRuby is a new library by Michael Neumann that makes it really easy (as in, even easier than RubyInline, although CplusRuby is of a smaller scope) to define custom C structures from within Ruby. The major goal of CplusRuby is performance, and the ability to easily define small methods within a class that compile to C and which can call each other directly. An example is always better than an explanation, so check out this code.