I've recently started donating my empty inkjet cartridges to The Nature Conservancy. I used to throw them away until I heard of this web site: http://www.donateempties.com. You just print a label at the site and mail in your cartridges free of charge. Everybody wins!
Wow, I have well over half a dozen empty ink cartridges laying around, but after taking a look, I see that they don't take the kind of cartridges my printer uses.