I must confess to have but scanned the many responses to this question, so forgive me if I am repeating something. I just wanted to throw in my two cents.
As someone has undoubtedly already pointed out, philo-sophy mean the love of wisdom, and in its first articulation in the literature of Plato, it is, to my understanding, represented as a way of life that is both essential to and a symptom of, any truly prosperous human society, and more specifically, any truly prosperous city. At its roots, it is not a “body of knowledge” or a “field of study” to be systematically organized and exhausted. Approached in this way, it is no wonder that one would see know use in it, because, in fact, it is not instrumental at all. It is a habit of thought and socializing at which we aim, and which we practice with our friends in order to better understand the place of our thoughts within our own being, and the place of our own being in the city. It is the end to which prosperous, free life tends, and in no “useful” way contributes to the attainment of any property or design. Indeed, in its original and most pure conception, the love of wisdom, borne out in the philosophic habits of thought and conversation in the city and the soul is happiness itself.
Academia, and specifically academics, have recast this way of life in their own image under career pressure and the envy of the progress “natural philosophy” made in its transformation into mathematical physics. Concerning this point I think it is useful to introduce a distinction between the history of philosophy and philosophy itself, and to acknowledge that the history of philosophy, as studied by actually reading the works of the dead guys, is incredibly helpful in the practice of philosophy, since it provides excellent examples of the habits of thought and conversation which befit the philosophic way of life and aid in the shareable articulations of the unspoken assumptions we hold about the world, and the consequences they hold for domestic and civic life, and our relationships with that certain divinity of self-reflection that every human mind most certainly possesses, however one might choose to conceive or characterize it. The history of philosophy furnishes many lovely examples of the beauty and power in the many forms of human thought that are inspiring and instructive as to how to live philosophic life in which concern for the self knowledge of our friends and ourselves is always the principal concern. The opinions of dead philosophers are often more valuable than our own because their opinions are expressed in polished writings that are the result of a lifetime of the cultivation of philosophic habits, and thus, even if their conclusions are not always the most helpful or even important to us, an appreciation for their methods of arriving at them can be very helpful in exploring our own opinions.
All value and worth in modern society from perhaps the time of Machiavelli and his contemporaries has been judged by the criterion of “usefulness” without really defining toward what end any pursuit or action is meant to be instrumental or “useful,” except insofar as it tacitly presumes the ultimate primacy of material wealth and military and political power in the acquisition of civic stability and individual happiness. Within this context, philosophy may not have a place at all, and it is up for one to decide for himself whether or not that is the case.
But we will always carry assumptions of which we are unaware, which color our actions and opinions, and which, unexamined, undermine the dignity of our species in its ability to make themselves conscious of its own thoughts if it so wishes. And I think, for the dignity of our being human, philosophy will always have a place in our lives together, as any thoughtful person with sufficient leisure to reflect upon it would, I think, conclude.
Whether this rambling response was of any help or not, I recommend reading Plato’s Meno, of which I believe the Jowett to be an excellent translation.