Lately in educational technology there has been a lot of talk about "flipping the classroom." What people mean when they say this is using instructional technology resources to use classtime differently. Instead of using class time to present content for the first time, teachers are giving assignments for students to do outside the classroom, then during class time they are helping the students to interact with the content. For instance, a teacher may assign students to review a video before coming to class, then use class time to further explore the content. In December 2010, eSchool News published an article about it. In July 2011, Harvard University Physics Professor Eric Mazur, referenced this idea at a educational technology conference.
There are many free online resources teachers can use to present content to students. One resource is Khan Academy which has over 2,400 videos on math, science and economics principles for students to use - for free. Wired magazine features the Khan Academy in July with the article How Khan Academy is Changing the Rules of Education.
Here is another article about using the Khan Academy in schools.
HippoCampus is a project of the Monterey Institute for Technology and Education (MITE). The goal of HippoCampus is to provide high-quality, multimedia content on general education subjects to high school and college students free of charge. Mind/Shift, a site about the future of learning, featured Hippocampus in February 2011.
On goal of online learning is to provide high quality content to all students - no matter where they live. Elearning for kids is a nonprofit foundation dedicated to fun and free learning on the Internet for children ages 5 - 12.
You may have heard that many colleges and universities offer access to their courses for free. Academic Earth is a search engine designed to help you find courses and videos.
SpongeLab is a great site with lots of interactives on science where you can create lessons to share with students. You have to register to create an account - but it is free for teachers.
By the way, all these resources work great on interactive white boards too!
Great article: Flipping for Beginners
Should you flip your classroom? Edutopia