Hewlett Packard (HP) will buy back your old HP electronics.
The HP Consumer Buyback and Planet Partners Recycling Program accepts products of any brand manufacturer in the following product categories:

* Desktop PCs
* Workstations
* Notebook PCs
* Tablet PCs
* Monitors, both CRT and LCD
* Printers, both ink and laser
* Digital cameras
* PDAs
* Smartphones

Go to the HP Consumer Buyback and Planet Partners Recycling Program website to see how much you will get.

Here is a list from CNET of 7 more electronics buy back programs.