Here's some snippets from City of Bones with some descriptions of the place where Simon and Clary go to hang out and ultimately meet the Shadowhunters.
"Inside, the club was full of dry-ice smoke. Colored lights played over the dance floor, turning it into a multicolored fairyland of blues and acid greens, hot pinks and golds."
"They were dancing, or what passed for it -- a lot of swaying back and forth with occasional lunges toward the floor as if one of them had dropped a contact lens -- in a space between a group of teenage boys in metallic corsets, and a young Asian couple who were making out passionately, their colored hair extensions tangled together like vines. A boy with a lip piercing and a teddy bear backpack was handing out free tablets of herbal ecstasy, his parachute pants flapping in the breeze from the wind machine. Clary wasn't paying much attention to their immediate surroundings -- her eyes were on the blue-haired boy who'd talked his way into the club. He was prowling through the crowd as if he were looking for something. There was something about the way he moved that reminded her of something . . ."
"Clary knew perfectly well that he came to Pandemonium with her only because she liked it, that he thought it was boring. She wasn't even sure why it was that she liked it -- the clothes, the music made it like a dream, someone else's life, not her boring real life at all."
Word is that fans saw the blue-haired demon on the set today. Although there weren't many pictures circulating on the set, I thought I'd share a few from around the web.