Mobile edition of Java. Current mobile devices either do not support Java at all, or support Java Standard Edition, but it was not the case in the past.
Since great majority of early and even some recent mobile phones supported Java Micro Edition applications (those are called MIDlets), this was the one of the most portable technologies ever created. Nowadays it's very hard to find a technology that spans so diverse set of devices, although there are several technologies that aspire to that status.