I was just snooping around on the Edmodo Science Community and I found a presentation posted by Eric Jones on Falling and Gravity. Very cool NOVA Science Now video embedded about digging a hole through the Earth, by the way.
I've never heard of Prezi before today...so cool!
Normally, the accounts with some bells and whistles cost about 60 dollars per year, but if you are an active teacher, you can get a free account with 500 megs of online storage space for FREE!
Click here for the link to the teacher account page.