I read the posting on Kitabe and SimplyAudiobooks. I haven't heard of Kitabe and I was a former Simply member but much prefer Jiggerbug for Audio book rentals because they are inexpensive (free trials, coupons, promotions and unlimited rentals for under $20) and they have instant downloads AND shipped CD's in one rate plan. For simply, I think if you want BOTH downloads and cd's by mail you have to pay for 2 rate plans.
Jiggerbug has 25,000 titles, and if they don't have what you want, they'll order it for you.
Their customer service is great which is more than what I can say about Simply and they get me my books A LOT faster than simply.

http://www.jiggerbug.com
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