I love it Greg... Styrofoam works outstanding for random rocks. I'm making some destroyed tombstones out of simple garage door insul sheets for halloween, and can't wait to deco them. Just need something like a soldering iron to cut and you're on your way really. (Niub Niub has good instructions on workign with stuff like this if anyone's curious).
The green beedy eyed guy was one of my most wanted JP aliens, and so he's getting a highlight now in your diorama and I think that rocks. I was going to rig up a smaller version of something similar on a shelf dedicated to Jabba's Rancor, actually. It's such a nice toy, it deserves a spotlight of sorts. And the figures to make it perfect help a lot too.
Looks great man, as always. I like your lighting... If you want cheap lighting ideas, visit 5 Below or the dollar store (just test it all before you put it into you set-up as bad soldering on that stuff can start a fire).