MMULib was developed as a standart for usage of the Memory Management Units, and was updated often, until the author's Amiga 4000 broke and now he is developing 8bit Atari emulator for Windows. The only software that requires it of which I am aware is ASp - the Sinclair Emulator, but the package comes with some utilities which may come handy. For coders the MUForce utilities is great (it's an enforcer replacement) and it saved me lots of headaches when debuging - it prevents system crashes as well.