Microman
http://www.takaratomy.co.jp/products/microman/
They all work great for the 1:18 Joe scale (I'm one of those who always refer to the scale instead of the 3 3/4 proportion measurement)
I collect Microman, they are intended for the collector and are not as durable for intensive play. But I find they are well worth the $$ :-)
You can also find them for sale at the following sites:
www.smalljoes.com
www.hlj.com (highly recommend Hobby Link Japan (hlj). Prices in yen, very good service, prompt delivery (within 7 days direct from Japan, and often times cost less than Big Bad Toy Store. They have diorama stuff too, lots of gems, but have to really dig into their site to find.)