This topic was broight to my mind by Paul Colligan and Alex Mandossian of Marketing Online Live, two guys that have a Podcast related to their Marketing Online magazine.
iPods aside, ask anyone in the business or marketing world, 'What business is McDonald's in?', and they will reply, 'Real Estate'. Most people will say, 'I thought they sold hamburgers and plastic toys and... fruit.' Oh no, my unknowing friend, think about it: