For several years I’ve been downloading spoken word books from audible.co.uk. My plan allows me to download two titles a month for £14.99 which can then either be listened to on my computer or, alternatively transferred to a portable device such as an ipod. While you can pay for titles without subscribing to a membership plan, if you are someone who reads a lot it works out more economical to go with one of the membership options offered by Audible (for example, as a non-member you may pay £20 each, for two books making a total of £40 but, as a member you would get both books for a total of £14.99).
One of the many advantages to Audible is that you don’t have spoken word CDs cluttering up your living room (before I started using Audible I often bought complete novels comprised of 5 CDs or more which sometimes fell on the floor spilling their discs everywhere)! Additionally it is much cheaper to use a service such as Audible as downloadable books are, in general much cheaper than their CD counterparts.
As a blind person I find the service very accessible (well it works well with screen reading software such as Jaws) so I’d certainly recommend it to blind people.
For US customers there is www.audible.com.