"Turn The Ship Around" by David Marquet An easy read because it's told in the context of a true story, sets up a great model for understanding motivation and competence. Although written from the leader's perspective it is revealing for everyone involved.
"How Successful People Lead" by John C. Maxwell A compact summary of Maxwell's 'five levels of leadership' concept. Was hard to find for a while, but it's currently available as an e-book.
"Managing Humans", and "Being Geek" by Michael 'Rands' Lopp These are a little more wild and woolly than the others, as they're more of a collection of blog posts than traditional books. But they give a much more approachable vibe to leading and growing your tech career, compared with most business books being pretty dry.