ProductivityPress.com is an entire web-site pretty much devoted to Lean. They sell a number of books. Personally, I thought the Toyota Way was the easiest read of the Lean books I have read so far. Most are pretty dry but worth the time.
We are currently carrying out a KANBAN trial on one of our product lines and I found that by researching this and 5S techniques they work really well together and are an easy intro to a full Lean System.