I'm using haxe+OpenFL. It's a pity that only a few people (and no one in this thread) actually using it because it's absolutely awesome. Haxe translates to the wide variety of different programming languages (C++, Java, JavaScript, Python, even PHP and Lua) therefore allows to make 100% native builds (no runtimes like java, .net, mono, etc.) for different platforms (one can build for windows, linux, android and html5 right away with minimal effort).