Audible offers New Audible Subscribers: 2-Month Audible Trial which includes 2 AudioBooks + $15 Amazon Promotional Credit for Free.
Note, offer not available to existing audible customers. You will receive a 2-month Audible free trial that includes 2 credits as part of the standard Audible Monthly Gold Membership Plan. At the end of the free trial, your membership will continue until cancelled at the then current full price (currently $14.95 per month) with your designated credit card or another available card on file.
source: slickdeals