I bought the Sony PRS-505 e-reader which will accept many of the downloadable e-book types, also got the illuminated holder for reading in low-light or in bed.
It will also play music and audio books via the SD card or Sony cards.
Not too huge either with an 8000 page turn battery life it can go through a few books before you need to recharge.
I've used audio books for quite some time and prefer when the author reads his own work, Bill Bryson's "A walk in the woods" being one of my favourites.
However the best I have heard so far was Rick Wakeman's autobiography "Grumpy old rock star" which lasted for 3 days as a friend and I drove around the highlands in September.
I don't think it's too easy to find these days but it's far more versatile than the Kindle.