The Indoor Writer has stories on Alfie Dog. You can download stories from 39p, so ideal for commuting or just sampling a writer's work. Three excellent stories to download here (someone has to do her PR!).
Another outlet for selling your stories is Ether Books, click here for more details. This site specialises in downloads to mobile phones, so ideal for reading 'on-the-go'.
If you write for the Womag market then check out the Womag Writer's Blog which regularly updates on new guidelines and any trends or news in the Womag market. Often lists some good competitions too.
If you know of any other outlets then let me know.