As an addicted to the Blender I found this project really interesting and fun! You can make a beauty mathematical models of the complex 3D surfaces with a few clicks!
This is useful modeling extension for 3D applications like are Blender, Maya, 4D Cinema, etc. So, if you enjoy in Escher's like 3D art you'll be hooked on this cool software instantly!
ZynAddSubFX is a powerful realtime, polyphonic, multi-channel MIDI synthesizer with built-in effects like: Reverb, Echo, Chorus/Flange, Phaser, AlienWah (a kind of vocal morpher), Distortion (Waveshaping), EQ, DynamicFilter. There are also filters, envelopes and other tools which can produce various reach and precise analog sounds. It's easy to use and it include a lot of cool predefined instruments settings.
Great companion for sequencer applications like are Rosegarden and Seq24. I really love this synth!