Instead of just recycling them, you can fill them with items you'd normally donate and have them donated for you.
Goodwill has partnered with a number of online retailers to offer the Give Back Box.
Just print out a USPS mailing label from their website.
Give Back Box will route your box to the nearest Goodwill store that's participating in the program.
Additionally, if you're willing to register for a Give Back Box account, you can get a tax receipt for your donation as well.
For more information visit: www.givebackbox.com