Shiny is definitely a cool project! I wish I would've known about its existence before I started my own project along similar lines. Our requirements were slightly different, since most of the stuff we want to do is pretty long running (Monte Carlo Markov Chain, shameless plug: http://mcda.clinici.co / https://github.com/joelkuiper/patavi). But for a quick interactive system, it's really cool! And once matured a bit more we'll probably end up using it in production.