So far, these are the themes we’re looking at:
For the Pets
Collars, leashes, and armor, like the equipment for horses. Amateurs/non-modelers could try making a prefab pet store or animal shelter, perhaps adapting the horse and henchman scripts to make the pets purchasable.
Dark Arts
I think it would be nice to do some things for demon/devil cults and necromancer lairs. Things like militated sacrifices, corpses in the middle of the autopsy, gruesome decorations, incomplete undead chained to wall, etc.
Mirror, Mirror on the Wall
A call for mirrors and other interior decor items. Both the mystical magical type of mirror and the mundane…From funhouse mirror mazes to elegant elven couches… this is a very open theme. I would request though that we try to supply items that don’t already have alot of coverage already, such as barrels, for example. Instead, a ladies jewelry box or a table with a half completed sewing project.
Colonial Times
Content that would help a builder bring NWN into the time period of the colonial era and Revolutionary War. Possible examples might be forts, cannons, muskets, clothing and uniforms, blockhouses, printing presses, and flags.
Beyond the Magic Mirror
Content inspired by the classic AD&D Modules, “Dungeonland” and “The Land Beyond the Magic Mirror”. Basically, Alice in Wonderland but adapted to D&D.
Skyboxes
New skyboxes - pretty self explanatory.
Arthurian Legend
Content inspired by King Arthur and the Knights of the Round Table.
Statues
There is a pretty limited offering of statue placeables, busts, and so on. Let’s make some more. Non modelers could script some devious traps that animate the statues or deliver harsh punishment to those unfortunate enough to disturb the statues.
Mythological Monsters
A Cerberus sure would be nice. Maybe even an updated Minotaur. I would also certainly not complain about a Kraken/Cetus so I can sacrifice Andromeda properly. Non-modelers could script spells and special abilities used by such creatures, or perhaps a prefab area such as Medusa’s lair.
As a Walled Garden is my House
Walls (could be placeable, could be expanded tilesets) that would allow us to surround noble residences, palaces and suchlike with something that does not look like built by orcs or is about to crumble. Also placeable walls matching the existing tilesets - both interior walls, to subdivide, and exterior “enclosure” type walls* for more versatile, harmonius use and placing at odd places and various angles.
Tools of the Trade
Holdable items indicative of civilian life - baskets of produce (I think I’ve seen that one somewhere, actually?), things like shovels or farming implements, crates, barrels or packages that can be carried by dockworkers etc., broomsticks (witch or street sweeper? you decide!)
Celestial Courts
Celestial beings of the higher planes. May prompt someone to make Biblical accurate Angel, since they are quite “popular” lately. Still, we have a lot of demonic creatures and assets on vault, so I think we could use some opposition. 
Eberron
We had Darksun, Planescape, Ravenloft… let’s give our favourite magi-tech setting some love! We now have some dynamic Warforged to go with this theme, so I feel that having some placeable skycoaches or other objects related to this setting would be pretty cool.
Fly me to the Moon
Lunar themed objects, tilesets, creatures for modern, fantasy or sci-fi settings!
Hunters and fishermen
Everything about hunting. New weapons and clothes and icons: rifles, optics, bows, complete with bandolier, fishing rods, fishing line, bait, floats, fishing tackle, waterproof leggings, nets. New game and fish creatures: hares, pheasants, quails, woodcock, partridge, partridge etc. Trout, salmon, pike, carp. Hunting dogs. New tiles and positionable. hunting huts, exposed animals, posable traps, slits, basket and feed with stick and rope, snare etc.
Everything about Insects
Models of life-size or giant creatures. Collembola, Dipluri, Tisanuri, Fasmidi, Diptera, Mantoidei, Tisanotteri, Odonati, Hymenoptera, Rincoti, Lepidoptera, Coleoptera, Blattoidea, Celifera, Ensiferi. Swarms of flies or locusts. Beetle and spider and other retextures. Parts of the body: Head and arms to insect tails, also other parts of the body. Beesman’s dress. Positionable: Beehives, honey combs, anthills, collections, decorated books, etc.