"A full reproduction of the original Roland TB-303 [...] The x0xb0x will never become 'discontinued,' because it is fully documented and released (under an appropriate open-source license). The PCB files (schematic, board, BOM and gerbers), firmware, software and panel DXFs are available for download. "
I do some quite extensive MIDI development using the awesome processing environment (check it out at http://processing.org/ ), but one thing that always left me unsatisfied was MIDI support. This comes both from the broken JAVA Midi support under OSX (check the previous post on osxmidispi), as well as the existing MIDI libraries being too complicated for my taste.