What do you write or keep in your battle book?

Important information pertaining to the company, rosters for key leadership and higher units, daily tasks to accomplish, notes for training schedules, training ideas, random bits of information that could help down the road.

Just about anything related to my position and possibly anything that could help newer LT's coming into the company.

As a Chemo I kept all of my agent info

As a PL I kept all of my platoon info

We all have developed our own products over the years. Start with this template of a continuity book and personalize it. http://sill-http://www.army.mil/30ADA/FRG/docs/Family%20Leader%20Team/continuity%20book.pdf