Project: libnetMD - free USB->MiniDisc software for Linux and Mac
Sonys interface to put music on MD-players is proprietary, cryptographically secured and the file-format ATRAC3 also digital restrictions management inside. http://libnetmd.sourceforge.net/ already reverse engineered all non-encrypted commands, but the most interesting one (copy music digitally via USB on the player) is not yet implemented. The free and open source alternative has stopped active development http://www.unmaintained-free-software.org/wiki/libnetmd due to technical problems. Cracking the DRM seems possible, but certainly not trivial.
Your task, should you decide to accept it, is to revive the project, add full support to libnetMD for putting music from the PC to the MiniDisc-player and adapt the GUI http://www.pdr.cx/projects/gnetmd/main/ to the new functionality so users can try it and verify your achievement easily.