It has local groups where you can offer things you no longer need or ask for things you may want or need yourself. I recently offered a defunct iPod speaker system and a local guy who is a technical kind of person was pleased to take it and see if he could get it working. Maybe he would then sell it - but if so, good for him. Much better than it gathering dust in our garage or even worse being put in the land-fill at our next inorganic collection.
Incidentally I also saw on Seven Sharp tonight a wonderful story about Kiwi Harvest a volunteer organisation that collects food that would otherwise go to waste and makes thousands of meals available to needy people. Look them up. It is inspiring what we ordinary people can do when we know the right channels and organisations to use or support.