What I think can be useful is SQL database of iNES mapper numbers, possibly using SQLite. I know how to operate SQLite, and can make such thing, you can make some suggestion/comment/idea/complaint in here, so that we can work to make it together.
Some of possible data might include: discrete/ASIC, rarity, extra audio channels, bank size, max PRG ROM, max PRG RAM, max CHR ROM, max CHR RAM, scanline IRQ, support of PowerPak, support of emulators, Verilog codes to implement it (if available), company that makes it, other features of mapper, and probably many other things I forgot about.
It might help if you can put the INSERT statements into the wiki articles of each iNES mapper number, and to make up another file which contains the CREATE TABLE statement, and then write a program that will download it and put it into one file on your computer.
Some of possible data might include: discrete/ASIC, rarity, extra audio channels, bank size, max PRG ROM, max PRG RAM, max CHR ROM, max CHR RAM, scanline IRQ, support of PowerPak, support of emulators, Verilog codes to implement it (if available), company that makes it, other features of mapper, and probably many other things I forgot about.
It might help if you can put the INSERT statements into the wiki articles of each iNES mapper number, and to make up another file which contains the CREATE TABLE statement, and then write a program that will download it and put it into one file on your computer.