BBC Dimensions - How Big Really is an interactive site that uses Google maps to allow you to compare the size of recent events to places you are more familiar with. It includes distances in space, deepest holes and environmental disasters. It has a companion site "How Many Really?" for visualising numbers.

Biology in Motion has original, entertaining, interactive biology learning activities for secondary science and senior Biology.
Freezeray offers a growing bank of imaginative, highly visual teaching-aids developed for use with interactive whiteboards. The resources are designed to be used as rich sources of visually stimulating material, making use of both animations and drag and drop interactivity.
Phet Science Simulations is a site with dozens of fun, interactive, research-based simulations of physical phenomena from the PhET project at the University of Colorado in Boulder, USA.
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The Scale of the Universe is an interactive site that allows the user to view the scale of everything from sub-atomic particles, to viruses, to bacterial cells to our earth, stars, planets and our universe. You can scroll in and out through familiar and unfamiliar objects, clicking on each image for more information.

From the makers of Crocodile Clips, "Yenka",has a range of free interactive resources for maths. physics, chemistry and electronics. Claims to be "The Perfect Simulation Software that's IDEAL for both Interactive Whiteboards and Individual Use." The most recent Edustar image has this software pre-installed (available to DEECD government schools).