I use Epiweb and like it alot. It does not degrade and you can cut the slabs in half to divide plants with minimal disturbance!
For the unnatural look you can grow moss on it if you have good light an high humidity. Look at this picture (from Karlboms orchids):
Growing moss on Epiweb 1.0
Take a good looking moss and mix with 2-3 parts spagnum moss. Run it with water in a kitchen mixer and filter it through a towel. Take the paste and rub it into the surface of the Epiweb. Keap moist and in good light and you will have moss growing within some month.
For more pictures on Epiweb with moss and orchids look at Karlboms orchids flickr page were you will find alot of inspiration.
EpiWeb - a set on Flickr