Well, let's see. I'll just name all the buildings I haven't got proper models for yet.
A Goblin Hut, Goblin Forge, Goblin Blacksmith, Goblin War Labs, Goblin Barracks, Goblin Tank Factory, Goblin Aerial Factory, Goblin Tannery, Goblin Depot and Goblin Refinery. (Refinery may actually be done. Although I will be complete it by smashing two models together into one).
Towers are basically covered. I may need to think of a cannon turret though.
The reason I started thinking about bazookas and rockets was because of this sketch I found made by handclaw.
http://handclaw.rampagingpolygons.com/ATT/GoblinDefense2.jpg
He also tried to create a goblin race at one point.
I got gatling gun, close range flame thrower.. but I think a bazooka turret of some sort could be cool. Also, I always did want to use the goblin rocket riders. But, potentially a launching place could be on the Goblin Aerial Factory.. Or you could just have a launching platfrom.. anyway.. I was thinking about mounting turrets on many of the buildings, allowing minor defense even without troops. ;P
Then again, I may just settle with the current towers.
Anyhow, There's also the idea of a goblin steakhouse. ;D
Here's two things, a concept sketch compilation I threw together a while back, with extremely tough models to create.
Some which I've tried and failed with multiple times.
http://www.hiveworkshop.com/forums/members/150231-albums4923-picture49381.png
Consider these inspirational. Also, a rough sketch of the games techtree.
http://www.hiveworkshop.com/forums/members/150231-albums4558-picture49789.png
I use this model as the Town Center.
http://www.hiveworkshop.com/forums/models-530/temple-boom-48630/?prev=d%3Dlist%26r%3D200%26c%3D20%26t%3D6
I also have a lot of inspration from Invader Zim. They seem very much like goblins, but in space. XD