Niche marketing is one of the most effective ways to make a lot of money off the web. It's about taking a general market and stripping it down into targeted and focused segments or niches. One then develops solutions that meet the needs of a specific segment.
Banks for example operate in many niche markets. At first glance, they may appear to focus on one market, the financial market. There is no doubt that this is correct, but banks perform a number of different functions by serving many different niches.