For anyone who may have collected this piece of LEGO history or wanted to should read this Brickset article. Here's the short of it.

Modulex Bricks were an offshoot for the LEGO company way back in 1962 to be used in architectural and commercial purposes. The pieces were considerably smaller than their standard LEGO bricks and could be considered on par in size with the current Nanoblocks product of another company. Talk of reviving the Modulex line spur until early January this year when it seems the parent company for The LEGO Group, KIRKBI/AS, cancelled the whole thing without any plans of future production.

To better help give some visuals as to the size of Modulex compared with regular LEGO bricks, here are some images and a Flickr group to check out.

 

Modulex - left / LEGO - right

LEGO - left / Modulex - right

Modulex - left / LEGO - right

Cool but those pieces seem almost too small to work with. Especially since these seemed to be aimed at adults/professionals. 

one interesting thing is modules is 5:5 ratio instead of 6:5 ratio. They would actually make nice Minecraft sets.

Cool but those pieces seem almost too small to work with. Especially since these seemed to be aimed at adults/professionals.

Indeed the pieces are very small and I thought a single 1x1 plate was tiny in my hand. I can only imagine trying to work with these without something like tweezers. They do allow roughly the same detail of regular bricks in a much smaller area though. I guess if you have little display room such as a desk at work then the Modulex subsystem would be beneficial provided one has the patience of fiddling with these tiny bits.

 

one interesting thing is modules is 5:5 ratio instead of 6:5 ratio. They would actually make nice Minecraft sets.

These would work well as micro-world versions of Minecraft or in this case 'nano'-worlds.