Anything high tech for halloween would be cool. Only wish I had the time to make something... Here are a few I like.
"Cybertech Wings" with onboard pneumatic pump for movement and has arrays of LEDs. A bit austentatious, but they require compressed CO2 to work, it is forgiven.
Michael Jackson's Billy Jean shoes with iconic lightup squares. They are directly attached to the squares. When the wearer steps, they light up. Pressure sensors, LEDs, and a housing. I'd rather not walk around on the light up panels, how about just project light on the ground around your feet?
My personal favorite, the DIY Daft Punk helmet. Made by Harrison Krix. Microcontroller based and packed with LEDs, only took 17 months to create. Read more about it here.