A great online "tour" of philosophy, its value, subfields, and applications from Ohio Northern University. An excerpt:
Philosophy is the systematic study of ideas and issues, a reasoned pursuit of fundamental truths, a quest for a comprehensive understanding of the world, a study of principles of conduct, and much more. Every domain of human existence raises questions to which its techniques and theories apply, and its methods may be used in the study of any subject or the pursuit of any vocation. Indeed, philosophy is in a sense inescapable: life confronts every thoughtful person with some philosophical questions, and nearly everyone is often guided by philosophical assumptions, even if unconsciously. One need not be unprepared. To a large extent one can choose how reflective one will be in clarifying and developing one's philosophical assumptions, and how well prepared one is for the philosophical questions life presents. Philosophical training enhances our problem-solving capacities, our abilities to understand and express ideas, and our persuasive powers. It also develops understanding and enjoyment of things whose absence impoverishes many lives: such things as aesthetic experience, communication with many different kinds of people, lively discussion of current issues, the discerning observation of human behavior, and intellectual zest. In these and other ways the study of philosophy contributes immeasurably in both academic and other pursuits.
The problem-solving, analytical,judgment, and synthesizing capacities philosophy develops are unrestricted in their scope and unlimited in their usefulness. This makes philosophy especially good preparation for positions of leadership, responsibility, or management. A major or minor in philosophy can easily be integrated with requirements for nearly any entry-level job; but philosophical training, particularly in its development of many transferable skills, is especially significant for its long-term benefits in career advancement.
Wisdom, leadership, and the capacity to resolve human conflicts cannot be guaranteed by any course of study; but philosophy has traditionally pursued these ideals systematically, and its methods, its literature, and its ideas are of constant use in the quest to realize them. Sound reasoning, critical thinking, well constructed prose, maturity of judgment, a strong sense of relevance, and an enlightened consciousness are never obsolete, nor are they subject to the fluctuating demands of the marketplace. The study of philosophy is the most direct route, and in many cases the only route, to the full development of these qualities.
I also appreciate these comments from Anthony Quinton, suggesting (to me, at least) that philosophy = critical thinking:
Most definitions of philosophy are fairly controversial, particularly if they aim to be at all interesting or profound. That is partly because what has been called philosophy has changed radically in scope in the course of history, with many inquiries that were originally part of it having detached themselves from it. The shortest definition, and it is quite a good one, is that philosophy is thinking about thinking. That brings out the generally second-order character of the subject, as reflective thought about particular kinds of thinking — formation of beliefs, claims to knowledge — about the world or large parts of it. A more detailed, but still uncontroversial comprehensive, definition is that philosophy is rationally critical thinking, of a more or less systematic kind about the general nature of the world (metaphysics or theory of existence), the justification of belief (epistemology or theory of knowledge), and and the conduct of life (ethics or theory of value).