Here's a fun use for discarded ink cartridges: turn them into the printhead of a new printer.
That's what Hewlett-Packard has done with its HP Photosmart D5460. The printhead of the new product is made up of 55 percent recycled PET plastic, which is made out of ink cartridges collected as part of the HP Planet Partners program. The D5460 also comes with a pretty cool software feature called Smart Web Printing that lets you adjust pages you're printing from the Internet so that you can define exactly what you want and don't want up printing all sorts of extra pages with extraneous content on them (like banner adds and navigation bars that you can't use on paper anyway).
In terms of eco-savvy materials, the new Photosmart model is a pale shadow, though, of the HP Deskjet D2545, which is made ALMOST ENTIRELY out of recycled plastics. (Something like 83 percent of the printer's total weight; plus, it uses cartridges that are themselves made from recycled plastic resin.)