Came across Thinglink from reading several blogs over the weekend, so it must be pretty good. Basically, they made some updates so educators and students can make up to 50 online photos interactive FOR FREE! And if you want to do more than that, it is pretty cheap too. I am linking you to a blog post by Richard Byrne of Free Technology for Teachers as he has a pretty good post on it plus a video showing you how Thinglink works. I could see lots of applications for students, especially for social studies students when using maps.
Richard Byrne's blog on Thinglink click here!