Rare language has both .Net and JVM support, probably only Clojure now. On the upside you can build iOS and Android apps using F# plus many other gaming platforms.
Clojure is far from the only language that supports both the JVM and CLR. I had a long reply ready, but I lost it. Off the top of my head the languages that have support on both (aside from Clojure) are; Python, Ruby, JavaScript, Java (though J# is being depreciated), Scheme, Common Lisp, PHP, Perl 6, Prolog, Pascal, Ada. I might be missing some.