Chris is on the right track. I already use both solutions, and it works out really well (35031 items in my $LDRAWDIR/parts/items/ folder and counting).
Note that items come in three varieties: primitives (hard-coded color), decorated, and assemblies, so this is not a simple case of "regular" parts in specific colors, there is true value to assemblies (multiple primitives that could be hard-colored or decorated with their attendant transforms in place), one that can't be solved by a "simple" database text file of associations of color + design, which has been suggested as a workaround.
-- joshua
Note that items come in three varieties: primitives (hard-coded color), decorated, and assemblies, so this is not a simple case of "regular" parts in specific colors, there is true value to assemblies (multiple primitives that could be hard-colored or decorated with their attendant transforms in place), one that can't be solved by a "simple" database text file of associations of color + design, which has been suggested as a workaround.
-- joshua