This website has lots of potential for setting context when teaching a novel or time period. Check it out--you insert a year and then lots of interesting videos are selected (advertisements, etc).
Broad Cam Pro--can turn your iPad into a live exhibit..your can showcase and interact with websites and materials on your desktop and record the video. Looks worth the $4.99.
American Museum of Natural History--great interactive website with lots of science and social studies information and games.. Kids can post questions. Appropriate for CA 7-12.