
If you can't acquire the Forces of Nature film (available on Amazon $17.99), you may want to consider a similar film from National Geographic titled Violent Earth. Violent Earth can be viewed for free on Snag Films. Using Snag Films you can also embed the Violent Earth video into your blog, wiki, or website. I've embedded Violent Earth at the bottom of this blog post.
Staying with the theme of forces of nature, Volcano World produced by Oregon State University has some great resources for teachers and students. I particularly like the virtual field trip through the Ape Cave lava tube at Mount St. Helens.