Maybe I'm crazy paranoid, but I physically destroyed 100 or so CD-ROMs before recycling them. Old backup files, mostly, ya just never know what could be on them (credit card numbers, files from Napster that someone working at my company could have downloaded, etc.). Simpler to destroy and greatly reduce the chance that something useful would be found by a resourceful data thief.
Obsolete or unrepairable CD's and cases can be recycled. Recordable CD-R's have about 20mg of gold that can be recovered, and some processors can actually remove the data layer, and reuse the plastic disc. If you are worried about proprietary data, you can cut them with a pair of heavy duty tin shears, or place them in a microwave oven with a small glass of water (for one disc, 5 seconds on medium does a fantastic job, and creates a spectacular light show)
Since CD's are not very valuable, nobody will pay you for recycling. Send pre-paid by UPS Ground, third-class mail, freight or other surface transportation to NESAR Systems, 420 Ashwood Road, Darlington, PA 16115 (724)827-8172 or Digital Audio Disk Corporation, Attention: Disc Recycling Program, 1800 Fruitridge Ave., Terre Haute, IN 47804-1788, (812) 462-8323a