Amazon has begun accepting Kindle ereaders in its trade-in program, offering discounts against future purchases if you send in your old model. Shoppers can get up to $135 for their old Kindle DX, or up to $48.75 for a 6-inch third-gen model with 3G.
If you've still been rocking your original Kindle, then the news isn't so great. Amazon will give you up to $29.25 for the first-gen model, assuming the condition as as-new. If you've been less than careful with the ereader, then you're looking at $18.50 for "acceptable" condition, which Amazon defines as fully-functional but perhaps missing one or all of the accessories, or showing scratches, marks or dents in the casing.
Should your Kindle be personalized, however, with a custom engraving or similar, don't expect to get anything above "average" pricing for it; we guess Amazon isn't convinced it will find a second-hand buyer with exactly the same name as you, wanting the same loving message from your wife. Credit will automatically be added to your Amazon account once the Kindle has been received and checked over.