Spongelab is an awesome interactive science technology site that I stumbled across in my research. It is free to sign up for and has so many uses I haven’t been able to explore them all yet.
The first thing you see when you enter the site is the Build a Body interactive lab. This application lets you choose a body system and walks you through placing the correct organs inside a human model. But you must have the correct anchor organ in place first. For example, in the skeletal system, you cannot connect the scapula (shoulder blades) and sternum (breast-plate) until you first connect the clavicle (collar-bone). And yes, I was also singing “the shoulder bones connected to the arm bone” by this point.
There are applications on animals and plants, DNA and cell division. You can search for an interactive lesson by topic or knowledge level (Beginner, intermediate and advanced.)
On top of all this, there are portals to create lessons, borrow pre-made lessons and communicate with other educators for ideas. You can save specific lessons and set up sites for your classes to access.
The ability to make this optional or mandatory is awesome. To be able to provide a physical model to visual learners on some difficult subjects, without having to have a full size anatomy model, is priceless. Especially for a teacher looking to provide opportunities to a small budget school in the ever-increasing world of budget slashes.

His Excellency plays Spongelab’s Build-A-Body, a recent recipient of a National Science Foundation Award.
http://www.flickr.com/photos/marsdd/6839757070/