They develop and provide commercial support for Akka, an actor-based concurrency toolkit (think Erlang) for Java and Scala, and Play, a web application framewor

They develop and provide commercial support for Akka, an actor-based concurrency toolkit (think Erlang) for Java and Scala, and Play, a web application framework for Java and Scala, among other projects. They're also major contributors to Scala itself, which is a multi-paradigm (oo + functional) programming language for the JVM. (I work with their software and the company I work for is a paying customer.)