Edited Jan 2017 to add - the app is now available on android devices as well.
Inkitt is a website where you can upload your novel and/or read others' novels. There's basic quality control (it can take up to 24 hours for a novel to show up on the site) for formatting and grammar. Then they use an algorithm that "analyze[s] reading pattern data and engagement levels" to decide if they'll offer you a publishing contract (they can publish it as an ebook themselves (you get 50% royalties) or act as your agent with traditional publishers (you get 85% of royalties - keeping in mind that a publishing contract for a mass market book usually gives royalties of 7-10%, so you'd get 85% of that. This sounds like they're taking the traditional agent commission of 15%, but I suck at math and may be missing something. Always consider your options and do your research before signing a contract)).
Today the company is launching their iOS app for Inkitt, so you'll be able to read and comment on others' stories on the go with an Apple device (iPhone or iPad), as well as have people read and comment on your uploaded novel.
I haven't used their service - I have too much to read as it is, and for review purposes it's better to use published novels (as unpublished novels might change before publication, invalidating your work) - though I'd have loved this idea back when I was writing instead of reviewing books. I also think it's a great option for commuters who get through books quickly and want to beta read books.
Here's a video showing off the new app and the app store link if you're interested. The app and books are free, though you do need to get an account.
Introducing Inkitt for iOS: Read great novels by up-and-coming authors on your iPhone and iPad from Inkitt - The Hipster's Library on Vimeo