Edublogs is an easy to use blogging program created specifically for teachers and students. You can manage your students involvement and participation at any time. I have created an eudcation blog, but in a math classroom, it doesn't get used very often. I do know teachers who use a blog consistently.
Google Earth allows you access to anywhere in the world and allows you to see geographic landscapes and terrain. Students have a a blast as geography can come to life!
Everyone is familiar with youtube and the material that can be found there. As school districts block more and more sites, the options for teachers becomes more limited. Teachertube is geared for educators and students and many of the videos are posted by other teachers.
Animoto is a great program that allows you to upload pictures, choose music, and wait as a finished product is produced in minutes. You can do a short video for free or get a full subscription and have access to longer videos.