EtherCalc is really impressive! We actually have this running on Sandstorm.io and were planning to release our port later this week. You can try it now as follows:

1) Click "start the demo" at: https://demo.sandstorm.io

2) Open this link to install EtherCalc: https://demo.sandstorm.io/install/100cdd4f5eb0ad2110b98a81c5...

(You can also install on your own Sandstorm server, if you have one, by substituting it for demo.sandstorm.io. Instructions for setting up your own server are at https://github.com/sandstorm-io/sandstorm .)

Thanks to Jake Weisz for this port, and of course the EtherCalc people for developing this and making it open source in the first place.