Beatesthesia is a highly customizable WYSIWYG music visualizer, inspired in motive and design by synesthesia.
It’s a free download, but is currently in beta form, so there’s a bit of a learning curve and you may encounter some weirdness.
Description:
Synesthesia has inspired many works of art. Art that is meant to evoke synesthetic associations in a non-synesthetic [...]

MachineCodex Software has announced the release of AudioCodex v1.0, a Mac media player on steroids:
AudioCodex is made for musicians, DJs, audiophiles and casual listeners alike. AudioCodex tightly integrates your media, iTunes Library, Quartz Compositions and CoreAudio Audio Units effects.
AudioCodex allows users to easily create loops and apply real-time Audio Units effects to tracks from [...]