If you are a do-it-yourself person, you could break down and re-use the mattress components yourself. There are many art projects that you can create with wood and metal springs. The fabric and foam can be crafted into a cheap pet pillow. However, you should be careful and follow online tutorials, because working with metal springs can be dangerous.
In the Future
Consumers are starting to demand more earth-friendly mattresses. Latex mattresses, which can be partially biodegradable, are a "greener" option when you purchase your next bed. Latex also tends to last longer than polyfoam and memory foam. However, latex hybrid beds will still contain metal springs that need to be broken down and recycled when the bed is worn out.
Working with your local government and community can help you bring a mattress recycler to your area if you don’t already have one.