History books are full of entrepreneurs and businesses who stuck to their guns and were soon out on the street. The most often quoted examples are Nokia, Blackberry, Kodak and Blockbusters, but there are thousands of others you'll probably never hear of. Conversely, some of the biggest companies that are still around today are almost unrecognizable from what they once were. Remember, Netflix started as a DVD rental business, and IBM now specialises in consulting and IT services.