I first learned about Glogster a while ago but didn't share it because it is one of those sites with a great tool but also a lot of user generated content that would not be appropriate for k-12 students to see or read. Thankfully, like so many other Web 2.0 tools, Glogster has come out with an education version of their tool that filters through the content more effectively and provides a safer learning environment for students.
So what does Glogster allow you to do? Basically, you can create your own online "poster" using images, text, video clips and audio files. They refer to these creations as "glogs", which I'm guessing is a take-off on blogs (maybe graphical blogs?) but that's just a guess. In a sense, a glog is like a single webpage but I think it also helps to imagine it as an electronic or online multimedia poster. There is a social networking element to this site in that users can create a profile and share their creations with others. I've included a sample glog below to give you an idea of what one of these might look like. Glogster has all the capabilities that you would expect as far as being able to embed your finished product and share it with others. The possibilities are endless with this and it would be very easy to incorporate into an existing website or Wiki.