"Every culture, gender, class, city, field of work, etc., has its own idols. Idolatry is anything I look at and say, "If I have that, my life has value." Anything that is so central to your life that you feel you can't live without it is an idol. Idolatry is making a good thing an ultimate thing. Because Paul saw idols everywhere, he was a really effective preacher. Like Paul, we need to discern, expose, and destroy idols in order to preach the gospel."
Tim Keller @ The gospel coalition 2009 conference. (read the notes here, or watch/listen to the full thing here)
Tim Keller also has a new book out on idolatry - Counterfeit Gods, see the video below for an introduction to the book (reading this on facebook and can't see the video? click "view original post" below)