I am not promoting rabid recycling, but I know this is a good idea.
Barracuda Coffee in Richland, Washington is recycling their coffee grounds. I know. You are wondering if they are trying to make more coffee with used grounds, right? Well, that is treason to a coffee drinker.
Coffee grounds are used to repel insects away from peas in the photo at right>
You can also use unused coffee that got old and tasteless, or coffee being sold cheap because it is old.
The only down side is that as you accumulate the used grounds they end up sitting in some container destroying the ambiance of your home.
Cold coffee that might be thrown out can also be put on plants to acidify the soil. This is usually only important if you live in the Southwest of the USA.