"Mod2PSG2 is a music tracker for the SN76489 sound chip running on MS Windows.
The SN76489 is used in various video game consoles, for example in the SEGA
Master System and Game Gear."
This is a tracker for windows, and you can write tracks for Mega Drive / Genesis. Nice demosounds, though. Nevertheless, the according website looks very dangerous, so be careful when downloading something. I don't take any responsibility.
"FamiTracker is a free windows tracker for producing music for the NES/Famicom-systems. The interface is based on MadTracker and should be easy to use if you've been using trackers before."
Very fresh software drum sequencer.
"By joining the "classical" oscillator-based electronics drum synthesis approach with simple FM synthesis, physical modeling of the drum shell, a powerful set of effects, and a beautiful user interface DKS is an unique, easy to use, and incredibly versatile drums synthesizer."