It's a directory of novels and serials on the web. If you write, you can get your story linked to, and people can review it. It gets your story out to a bigger audience. If you read: it's all free, and good original fiction of various genres by various authors.
Alexandra Erin is popular enough that she could quit her job and live off of donations because people love her writing that much. This is pretty inspiring for authours and suggests that people looking for a good read might like her stuff.
Where do I come in? Well I read a webcomic called sorcery 101, and one day there was an interesting ad for what I thought was another fantasy webcomic... only instead of pictures it had words. So I clicked, and found the first chapter of a story. It's called MU Tales, and it tracks a niave half demon through her adventures at university. I was in love, I am hooked. Only the author is taking a break for Christmas so I found myself clicking on her site: pages unbound. It's like a little library. I think i'll come back and browse it when I want some good easy to get fic to read. :)