I gave this talk Starting Lean - Running an Agile Enterprise to a group of founders of mostly small businesses. You can view and download the slides from the link.
The talk is based on Ash Maurya's book, called Running Lean, a firm favourite because it's so practical.
Think of this as Lean Startup applied to an existing business, which is exactly what Eric Ries himself did.
Eric wrote about that experience in his sequel The Startup Way which explores 'intraprenuership'.