If you use Goodtools and the rename "dirs" command, it will split your set up into directories based on country code, bad dumps etc... Most of the screenshot packs at my site are based on just the "USA", "World" or "Euro" gooddump roms which end up in those directories after using goodtools.
Unlike mame roms, console rom sets consist of thousands of roms with most games having a large number of multiple copies including many bad dumps, over dumps etc.. By using goodtools and the dirs command, you can weed out most of the crap. - Most console rom sets can be gotton down to about ~600 decent USA roms.
If you really love console roms (as I do!) I would seriously consider grabbing a full set of them off a burner like you do with Mame. That way you'll have a decent set which you can grab out a full USA or World set from.