This looks really cool. I always wanted a small embeddable JS engine with a C interface. And it looks like you modelled the C API after the Lua C API? That is what I wanted as well.

Here are some related projects I saved links to. I think there were a few others.

http://code.google.com/p/tiny-js/

http://adaptive-enterprises.com/~d/software/see/

http://sourceforge.net/projects/njs/

v8 is an obvious open source implementation, because it's packaged separately (and used in node.js), but its API is C++ and relatively complex. For a lot of applications, it's overkill.