Hi, We are not "permitted" to use Skype so instead our district has provided us with Polycom. Obviously it is not as seamless as Skype since Skype is used by more individuals, so I was disappointed to learn we cannot use it in our buildings. However, once we got our guests set-up with Polycom, we have conferenced with an author for our upper grades and one student in our building has an uncle who works for the company who builds the mobile arm on the space shuttle so we confereced with him as well. These opportunities definitely excited the students and really get the teachers geared up for how they can now incorporate additional conference ideas into their teaching. If you could collaborate with a class across the country, or world, I think that would be another great way to learn/study about communities and compare/contrast our towns/states/countries.
Hope this helps!