Android - Ruby, Python, Clojure, Java, Common Lisp, Haxe, C#, HTML5, Scala, C++, C, anything that runs on the JVM or translates to Java, anything that compiles to native code. Basically everything. Some are easier than others.
On my phone there are commercial apps that run on Clojure and Haxe, two fairly obscure languages.
iOS - ObjC, Ruby, Common Lisp, Haxe, Java, HTML5, C#, C++, probably others...
Android - Ruby, Python, Clojure, Java, Common Lisp, Haxe, C#, HTML5, Scala, C++, C, anything that runs on the JVM or translates to Java, anything that compiles to native code. Basically everything. Some are easier than others.
On my phone there are commercial apps that run on Clojure and Haxe, two fairly obscure languages.