This was one of the most clever promotions I heard of at CES: The people that make the Jawbone Bluetooth headset, one of the more readily lusted-after Bluetooth units, were giving away free ones for anyone who would trade in their old Bluetooth headset. Jawbone then recycled all the old ones.
It wouldn't have worked if the Jawbone wasn't a premium product in the minds of show-goers. The company got to write off several thousand dollars of inventory as promotional expense while at the same time forcing a bunch of presumably-more-influential-than-average tech nerds to sport their product.
Jawbone's Gallery of the trade-in [Flickr]