SCDPlay is a program that can play the videos in STM format you can find in your CD of Sonic CD for the MegaCD. It can also dump video and sound data from the videos to bitmaps and WAV, respectively.
Gens is a Sega Mega Drive (Genesis), 32X, and Mega CD emulator with a GUI with many features.
A partition or disk cloning tool similar to Symantec Ghost.
The most POSIX compliant and fastest known implementation of a tar archiver.