Noticed an offer in Sunday's BestBuy ad, about trading in various types of hardware. Mentioned were Zunes and iPods. Checked it out on their web site and found I could get a $37 BB gift card for a 30G Zune with cable and charger. (even the brown one) That seemed pretty decent to me, since with an 8G, an HD and an 80G, the 30s were just collecting dust. I had some old style chargers which were bigger than the Zunes which I wasn't attached to as well, and cables galore.
Process was simple, take them to the store, fill out some paperwork and they gave me a gift card. Who can't use a BestBuy gift card? Trade-in is less if you want a check, and considerably less if the device is engraved. Certainly more convenient than trying to eBay or Craigs list them.
Zunes/iPods aren't all that is eligible. http://www.bestbuy.com/tradein