We are a LEAN startup. We have been from the start, and it really means something to us. It probably doesn't means much to you, and that's why I'm writing to say you need to pre-order a book. And not an ebook, but an honest-to-God "dead trees" tome. Here's why.
We have built an operational service very efficiently by making informed guesses about what our business will be, prototyping our theories quickly, responding to real operational issues, learning from our experience and building what he discover is actually needed.
You can think of what we have built as "policy-based access to content", as opposed to "open access" (think YouTube and Flickr) and "social access" (think Facebook, Dropbox and Google Docs). In most cases, the policy that matters is that someone's payment has succeeded and our system automatically fulfills a file or subscription. It's a pretty simple concept but getting the systems right is about our process, not our ideas.
Eric Ries is not the only one pushing Lean Startup ideas, but he's done the most comprehensive job of forming and proving the arguments for building a startup the way we are. While we are built primarily on a Java technology stack, Eric gave a very nice presentation at the most recent RailsConf 2011 and most of all of it applies to us.