Just a few books to consider:
PMI-ACP Exam Prep, Premier Edition – Great read for those prepping for the PMI-ACP
Agile Samurai – Easy read for getting some of the concepts quickly.
Agile Retrospectives – Lots of interesting ideas for keeping your Retrospectives fresh.
Agile Government Contracting – Help for those dealing with complex Agile contracting requirements.
All in – Inspiring read for entrepreneurs
The 100-Year-Old Man Who Climbed Out the Window and Disappeared – Great book for a break from tech
Scaling Software Agility: Best Practices for Large Enterprises (Agile Software Development Series) – Go to book to get going on Agile in large companies