These are the hightmap files ive found and/or created sofar in my attempts at building areas, they are by no means perfect in any way, and some may require a few modifications to work properly
(i use YATT for might hightmap to nwn2 dealings)
List:
1. Clover Isle - Properly sized to fit a 8x8 area, Found on the net, croped and edited for an nwn2 area, it makes a perfect 3d clovershaped island, complete with hills
2. Cresent Isle 2 - Hand made in photoshop, its supposed to be an area in my upcomming mod, i never got it working completely right, but its close, makes a 32x32 area