Here are some books recommended by members of the Balanced Team Group. They cross a variety of disciplines and methodologies. Think something should be added? Let us know in the comments!
User-Centered Agile Method by Hugh Beyer
Four Steps to the Epiphany by Steven Gary Blank
The Entrepreneur’s Guide to Customer Development by Brant Cooper & Patrick Vlaskovits
The Back of the Napkin by Dan Roam
Unfolding the Napkin, The Hands-On Method for Solving Complex Problems with Simple Pictures by Dan Roam
101 Things I Learned In Architecture School by Matthew Frederick
Agile Software Development with Scrum by Ken Schwaber & Mike Beedle The book that formalized Scrum.
Extreme Programming Explained: Embrace Change by Kent Beck The book that formalized XP. Both the first and second editions should be read - they’re interestingly different.
Implementing Lean Software Development and Lean Software Development: An Agile Toolkit by Mary & Tom Poppendieck Early books that really looked into applying lean concepts in a software context.
Kanban by David Andersan