For something even smaller, download miniPicoLisp.tgz. It is a minimal version, without support for databases, UTF-8, bignums, IPC, networking and other system-dependent functions. A kind of "pure" Pico Lisp (not "pure Lisp"!). It supports the full Pico Lisp language, but runs faster, and uses even less memory space. It should also not be restricted to Unix. In addition, it compiles and runs also on 64-bit systems.
Jon Kleiser wrote an OpenGL library gl.tgz, and a Chinese Checkers program running on top of it.