ixlib by Andreas Kloeckner provided the (to my knowledge) first freely available C++ javascript parser.
boost::python by Dave Abrahams for several ingenious techniques when dealing with function pointers with variable number of arguments
A lot of the overall interface design is also inspired by the boost::python library
boost::spirit by Joel de Guzman and team. Amazing parser generator framework written in C++. Used for the javascript parser
The documentation templates used here are copied from the Spirit project
boost::mpl by Aleksey Gurtovoy. Provides tools for metaprogramming
boost::preprocessor by Vesa Karvonen and Paul Mensonides. Makes working with function pointer templates with different number of arguments a dream.