Beatesthesia is a new open-source, cross-platform VJing/music visualizer application programmed in Processing. It sports some interesting design decisions, including an audio-reactive user interface. Its an interesting idea, and is certainly pretty and definitely novel. At first glance, I didn’t like the blinking UI; it struck me as being far too distracting, but, after second thought, it’s a pretty decent way of conveying content and disambiguating a UI elements purpose. Well done. Check out the Vimeo video and home page to get a feel for its capabilities.
Beatesthesia strikes me as being more of a music visualizer than a fully featured VJ application, but it’s open source, which means it will grow as it pulls in a dedicated user base. Beatesthesia’s website also hosts shared projects, so you can explore other users visualizations. [Ed. For what it's worth, it looks like more than just a visualizer to me -- especially as you start to edit the ways in which it works and make more elements "performable" -- and if you don't like this specific implementation, you could certainly code your own in Processing! Anyone performing with this or building something similar, let us know. -PK]