Currently I'm developing a brand new filter for ROM files (NES/SEGA/SNES games). I'm not sure about list of supported ROMs - it depends on my tests but I think at least one of these must be supported:
NES - Nintendo
BIN - SEGA Genesis/Mega Drive II
SMC - Super Nintendo
Z64 - Nintendo 64
This filter will be some kind of Disassembler oriented on compression. Also here you can post your suggestions about supported ROMs, ideas, etc.
I think this feature can make PIMPLE really popular and EMU-gamer's #1 choice. Also note, even without this filter PIMPLE achieves superior compression on ROM files...