A VGM Player has been released for the NES by "mic". What's this then you ask? Well it allows you to play music created for the SEGA Master System on an NES. The zip archive contains a player som and a rom builder tool to insert SMS music into an NES ROM.

Well for more technical info check out http://jiggawatt.org/badc0de/nesvgm.htm

Download Revision 1 here.
Download Revision 2 here.