There are several other languages available. For instance, Jython (Python implementation in Java). The way to use other languages is by adding the JAR file to CLASSPATH and making a reference to the right name.

For Ruby, there is JRuby. See the following: https://github.com/jruby/jruby/wiki/JavaIntegration

ScriptEngineManager m = new ScriptEngineManager();
ScriptEngine rubyEngine = m.getEngineByName("jruby");