WD has a recycling deal where you can get 15% off your total purchase, once per quarter, by sending in any drive, working or not, to their recycling partner. I just did this with an old Maxtor 60gb 3.5” PATA drive. The shipping is free and it gets processed really quickly (e.g. it was actually delivered today and i already received -and-used- the discount code.

Note that theyre pretty clear/strict about no stacking of codes/discounts.