Some effort is being made to bring other languages to the web. Emscripten is a backend for LLVM to produce javascript code (should work with any LLVM frontend).

Some effort is being made to bring other languages to the web. Emscripten is a backend for LLVM to produce javascript code (should work with any LLVM frontend). NACL (native client) is a project by google to allow code to be compile for a more secure subset of x86 and to run on a browser safely. I'm not sure on the stability or use of either. GWT (google web toolkit) is a project that compiles java to javascript. This one should be fairly stable and seems to be well supported.