UPDATE: Instead of a $5 voucher, Audible now gives you two free audiobooks when you sign up!
If you signed up for a free Audible.com trial membership last week (or are already a member), be one of the first 100,00 to add $5 worth of free credit to your account. Simply log-in then visit this promotion page to get the free credit.
I'm not sure if they have any items listed under $5, but how about this. For $5, I'll come to your house and follow you around for a few weeks while periodically reading aloud your latest book.