I just use it offline, on my laptop. The UI is just a nice frontend to an idea that you know will work. Then you might have a ton of ideas that you want to check before publishing. One question may want to answer is if the behavior on HN predictable?

Google App Engine doesn't support R but you can use NumPy:

http://code.google.com/appengine/docs/python/python27/using2...

http://numpy.scipy.org/