Discovery Young Scientist Challenge:
National
Science Fair competition for middle schoolers in grades 5-8.
http://school.discovery.com/sciencefaircentral/dysc/
Toshiba/NSTA ExploraVision Awards:
Contest
open to students K-12 who work in teams to explore their vision of future
technologies.
Siemens We Can Change the World Challenge
Middle school students are challenged "to create sustainable, reproducible environmental improvements in their local communities."
http://wecanchangetheworldchallenge.com