Rob Walling (http://www.softwarebyrob.com/ http://www.softwarebyrob.com/) has a book called 'Start Small, Stay Small' that sounds like what you are looking for.

Rob Walling (http://www.softwarebyrob.com/ http://www.softwarebyrob.com/) has a book called 'Start Small, Stay Small' that sounds like what you are looking for. He talks about finding a problem to solve, and has lots of practical tips and advice on how to determine if there is a market for the solution.