There are a lot of languages that are implemented in Common Lisp.

Now, unfortunately, it's often only the early implementation of a language that is written in Lisp.

cl-python
http://common-lisp.net/project/clpython/

There's a r4rs scheme implementation named Pseudo.
http://www.cliki.net/PseudoScheme

An early implementation of Yale Haskell.
http://www.cliki.net/Yale%20Haskell

"In ~2003, Mozilla's CVS tree still contains the original implementation of Javascript... written in Common Lisp."
Well, the mozilla/js2/semantics/README that I just checked-out from mozilla CVS says:

    js/semantics contains experimental code used to generate LR(1) and LALR(1)
    grammars for JavaScript as well as compile and check formal semantics for
    JavaScript.  The semantics can be executed directly or printed into either
    HTML or Microsoft Word RTF formats.

You may also be interested in Zeta-C although it's not written in Common Lisp http://www.cliki.net/Zeta-C.

maxima (which implements a mathematical language similar to macsyma, ie. similar to mathematica, octave or mathlab).
http://maxima.sourceforge.net/

acl2 (which is a theorem prover) implements a lisp-like language in CL.
http://www.cs.utexas.edu/~moore/acl2/

Qi is implemented in Common Lisp.
http://en.wikipedia.org/wiki/Qi_%28programming_language%29

Here is a toy implementation of BASIC in CL:
http://www.informatimago.com/develop/lisp/com/informatimago/small-cl-pgms/basic/

And the implementation L.S.E (Langage Symbolique d'Enseignement, a French programming language of the 70's):
http://nasium-lse.ogamita.com/
http://fossil.nasium-lse.ogamita.com/nasium-lse/dir?ci=tip

And a few more, see http://www.cliki.net/programming%20language
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