The recent spate of unarmed mecha is a result of the Mecha Hub Civilian Mecha Contest on Flickr. Kyle Vrieze (bermudafreze) has built a pair of my favorites.
Micro mecha aren’t that unusual, but placing the mecha on a microscale background is fairly unique:
This submersible mecha has realistic, utilitarian arms:
See more great entries in the Civilian Mecha Contest thread.