In the Digital Curation project for my Tech course, I looked at two recommended tools: the Smithsonian Learning Lab, and elinks.
The Learning Lab shows great promise but is still early in the stages of development and would require quite a lot more teacher prep time. It is, however, an excellent tool for allowing students to explore primary sources that address many topics discussed in elementary social studies lessons.
On the other hand, elink was a great grab and go technology that would not take much to get students online using and sharing. One way in which it is weak is its organizational ability. You can decide the order in which links appear, but if you have an odd number and you wish to create something more like a T-chart, it is not possible. That said, it does lend itself well to the ability to browse and gives your students options in what they wish to look at and in what order.
It will take some time and usage to get the hang of the best way to implement these tools, but they have great potential to bring subjects to life and challenge students to look at their sources more critically.