Holy moley! Been a year and a half since I initially posted this.
There has been a game released written in Common Lisp. It's called 2x0ng (that's a zero) and it's sort of an abstract roguelike, in a way. Reminds me of something out of TRON.
I am mainly studying functional programming in order to get better at other programming, if that makes sense. I still do not *get* LISP but I have been able to glean a number of benefits out of it, like better understanding of recursion and a number of other things.
I should totally read Land of Lisp. I have been studying it from SICP, and from the MIT and Berkeley Youtube lectures that go along with that.