I have long desired being able to run clojure code directly in my Common Lisp environment. Interop between clojure code and CL code would be much more interesting to me than the clojure/java interop. Yes, there's ABCL which does the CL/Java interop (and of course vanilla clojure has that built in), but I'm a big fan of the idea.

And ruricolist has written (and maintained/forked) some nice libraries. In particular his FXML is the modern successor to cxml and plays nice with xpath, etc...