Thanks to Yazdan Mansourian for reminding me about the Illinois Mathematics and Science Academy (USA)
Digital Information Fluency website. I've not actually been back to it for a while (they linked to our Christmas Quiz a couple of years ago...) and I think the site has been redesigned since then. It has a lot of interesting content including "micro modules", little exercises, annotated bibliographies, lesson plans that teachers have submitted etc.
http://21cif.imsa.edu/