@mhaze: this is quite simple. I created a simple plane with four or six length and width segments with a length of 150m. I then added a greeble modifier with minimum and maximum height of zero, but taper of twenty. No widgets. If you check "select top" and add another greeble modifier you'll have space between the blocks. You can play with the settings and use an edit mesh modifier to select some faces you want the next greeble modifier to be or not. So you can add several instances of greeble, but be aware that at some point your RAM won't be enough.
