Try these two sites for 5 of the 6 maps:
1.
http://www.nothingbutneopets.com/home.p ... reasuremap
I like this one the best, but I don't know how long ago it was written, as the pricing listed is way out of date.
2.
http://www.cloudneo.com/neohelp/tmaps.shtml.
It shows 5 of the 6 maps and they are completed. So, you might want to copy and paste them into Paint and draw three lines evenly across and three lines evenly down to figure out what each piece looks like.
I haven't yet found a full picture of the petpet lab map, though I am still looking.