Share tweets publicly based on hashtags or other searches. Great for feedback. You could even use them in class to see what people are saying about current events.
This is a great site that students can practice and learn about all the continents, world maps, rivers, lakes, monuments etc. Students are timed and they really enjoy trying to better their score.
Fantastic article from a Christian writer discussing the failings of the proposed internet filter, and providing practical steps for keeping our kids safe in an online world.