I am highlighting the US history one, but there are many great ones at this site. I found that even though many are listed for older children, there were pieces in each one that I could use with my 3rd graders--either as a whole class lesson or as an extension for some of my high-achieving students.
The US history map above has some pretty nice features. It breaks US history into categories, does a short lesson on it, and then has students participate in an interactive review. You can skip through the eras if you don't want to do them all. At the end of the map there is a comprehensive review assessment that students can do and receive their score.
Check out these interactives. They cover all content areas. I think they are worth your time!