Here in the Lehigh Valley PA:
For my 11 year old DD
Uggs
skinny jeans so the Uggs look right (of course

)dark blue or medium, no light or black allowed
Chuck Taylor Converse in Black ONLY
long straight hair with loose curls on the bottom
Peace signs seem to be dying out
Justice seems to be dying out as too girlie in favor of a more androgynous look
Abercombie t-shirts
Aero t-shirts
White cropped winter coats, or other as long as it's cropped
texting phone with a cool plaid cover
being an athlete
For my DS12:
Snow boarding
and all the gear that goes along with it from a specific jacket to the cool helmut and, of course he NEEDS a Camelbak
Texting phone
I-pod Touch
Skateboarder shoes are still in as long as they are Fallen or DVS
straight leg pants, not the girl skinny
longish hair
skateboarder backpacks
Abercrombie T-shirts
Aeropastle T-shirts
Thick fleece lined hoodies from Pac-Sun, never a regular old winter coat
being an athlete
Oh, and both kids love smelcils, which are scented pencils made from recycled paper instead of wood.

I don't know where these kids get this stuff from but if I'm buying a coat or shoes anyway I don't mind a brand if it's what they really want and good quality.