Hi
I've been working in a personal project about extra material for games (screenshots, covers*, savegames, etc...) for a while. I store all the extra material renamed to an unique alias for each game extracted from the DAT files. This way I can forget problems related to name changes, this kind of works if done by projects like yours.
For MAME I'm using standard 8 letter alias and for No-Intro games I'm using ROM's CRC32. Unfortunately I've noticed you don't store this kind of information in your DATs. Could you please add this information to the DATs; you already have Disc number id in your online database wich will be perfect; it shouldn't be too difficult (I think) and it will help a lot projects like mine.
Here are some examples of my current progresses (maybe the project will be made public someday but it still needs a lot of work to be done):
Kind regards and thanks in advance.