I have been a member of audible for a while now, I am currently a premier member, so I pay $20 a month and get to pick 2 titles per month, plus I believe I pay less for other titles that I purchase. I just finished listening to 14 hours of unabriged "Timeline" by Michael Crichton. They have a very extensive list of titles, such as William Shatner reading exceprts from "Foundation" by Issac Asimov.
Then there are the subscriptions they have available. Almost every program on NPR is available, every M-F morning, you can download and listen to the NY Times top stories in the different sections (very nice), Robin Williams interviewing different people (I think he might have stopped, but check out the archives, they are so funny that when I listen to him on the bus to work, I sometimes have to pause playback to kee from busting out laughing. Then they have Susie Bright, the smartest online radio show about sex that you will ever hear. Men and women will equal appreciate her sense of style (if you are interested in sex that is).
I would start out at the basic level which gets you one book and one subscription per month (that is a one month subscription to any subscription item, some are daily, some are one or two per month).
Some other notes about the service, anything you pick as part of your membership "package" is yours forever (or until audible goes bankrupt). This is nice, as it allows you to delete you downloaded files once you have listened to them. If you have a broadband connection, just go for the best quality file, my 15 hours of Timeline was only 230 MB, broken up into two equal length files. That is not bad. The highest quality is about a quarter of the size of an mp3 file. The smaller files are only useful if you are stuck on dialup or are using an audible player with no storage space.
If you join, and you can't think of anyone to put down as someone who refered you, just tell them that
peterjhill@stargate.net recommended them to you.