How to find startup ideas that make money

I am glad that my previous blog post Sorry, your “cool” webapp is probably not going to make money received good response and generated a lot of debate. What I discussed in that blog post was that most of the so called startups or webapps which are based on “game-changing” or “cool” ideas never end up making any money. So, if your aim is to make money, pursuing such ideas can be risky. While