Embedded programming languages are really cool. Lua's still ruling the roost, as far as I've seen, but there are some nice options out there.
I'm currently using mruby for a project and have been quite happy with it so far. The community around it is still somewhat thin, but the code quality is good and development is quite active. https://github.com/mruby/mruby
I read that Io is frequently used as an embedded language. It's really nice, OO and prototype-based little language, definitely worth a look.
Out of interesting Lisp dialects, there's also PicoLisp (http://picolisp.com/wiki/?home) which looks like it should be well suited for embedding, but I didn't find any docs for how to do this with a quick search.
I'm currently using mruby for a project and have been quite happy with it so far. The community around it is still somewhat thin, but the code quality is good and development is quite active. https://github.com/mruby/mruby