Curvecalculator.com started as an exercise to teach myself some modern internet technologies, d3.js being chief among them. I chose to implement a curve calculator as it a well defined problem that nonetheless offers some interesting options for developing a useful interface. I've opened sourced the code for this page on GitHub page, if you're interested in taking a look underneath the hood.
The application itself is written in d3.js, a leading visualization library for JavaScript. The rest of the site is statically generated using Jekyll. Hosting is provided by Amazon's S3 service.