Otto is an open source music jukebox app that disguises itself as an iTunes replacement without all the extra baggage, but is actually a web-first, fully streaming, anti-cloud, social music server that allows multiple people to listen to the same stream of music at the same time and DJ for each other. Kinda like a private turntable.fm. For Mac OSX and Linux. A limited demo loaded with some CC licensed music can be found here. [more inside]
This web-based application will plot the Mandelbrot set, let you zoom in on different sections and link to them (e.g. here). It requires a recent HTML5-capable browser (Firefox and Chrome both work). Source code is here under an open-source license. The website is entirely static. All processing happens on the browser.