Been playing around with a pre release version of Amie Grid Calculation Engine, made by the guys from Recursa. The current front-end application is an Excel plugin allowing the calculations to be done by the Grid Engine.
As new toys go it's really fast and fun, once you are connected to the Grid Services. I had to learn all about Narada Brokering so I understood what the communications did. This because they've asked me to build an AJAX front-end, attached to the broker. Then it can easily be intergrated into webapps.