I found out about these terrain pieces from the Beasts of War, who have a series of excellent unboxing videos:
I realised that they are perfect for both 40k and Epic scale games. Unfortunately they're extremely hard to get hold of! It took me a while but I finally tracked down a box of them on the Marquee Models website (they're now out of stock on there as well).
I decided that I wanted to base them so that they'd be more stable on the gaming table. Taking my trusty compass cutter I made some based from 1mm plasticard and glued them on. All I needed to do then was apply some Basetex textured paint, some Devlan Mud, and then the same flock that I use to base my Epic necron models. Here's the result: