I know there's some competition out there for whiz high school kids, but I'm looking for something more geared towards an advanced middle schoolers. The problems should be simpler than Project Euler or SPOJ and be language agnostic (or at least accept Python).
Alternatively, if no such sites exist, are there any programming challenge "packages" for setting up your own site and filling it with problems you create yourself?
Update: I'm not looking for a programming language for children. I'm looking for challenges I can point a child at in order to learn their language better.