Lisp

I have a minimal amount of experience with Lisp and have read the blog posts on how to implement the basic special forms which are needed to define a Lisp. I'm considering trying to write my own Lisp as a scripting language for a platform whose primary language is something that I don't like. Thing is, I don't really want to write code using a minimal set of primitives. I want to write in a full Lisp.

Are there any "bring your own bootstrap" Lisp implementations, which provide a more full-featured language once the basic primitives have been provided? Something that would let me go more quickly from a couple hundred lines of bootstrap code into a more full fledged language, even if the runtime is slow.