towave is a program I wrote that takes a chiptune file (NSF, GBS, and several others) and asks for a track and a length of time. It then generates WAV files of each of the channels by itself, playing the given track for the given amount of time. I wrote it to make covering video game music a lot easier, since I usually have the GBS on hand while covering. After running towave, I just throw the WAV files at Audacity and work with the song visually. towave is licensed under GPLv3. Learn about free software and the GPL.
Windows - Source
(I've only tested the program on my Windows 7 64-bit machine, but I see no reason why it wouldn't work with at least XP. As for other OS's, I can compile for Linux, but I don't have a Mac nor any other OS available.)
rel3 - Officially licensing towave under GPLv3.
rel2 - Bugfix: If track 1 begins in silence, its silence was skipped.
(various mucking about with DLL's between releases)
rel1 - Initial release.