A good business must always solve a customer problem. I was wondering, for B2C type of opportunities, where would one look for complaints? What are the places with the highest complaint-to-noise ratio?<p>One example would be to search Twitter for "I hate when...".<p>Any other ideas?
I will suggest that one way to find big problems that can make a major difference if solved would be to look for things people talk about as <i>a necessary evil.</i> It signals that they know it sucks as a solution, having no solution is so much worse that they are willing to accept the downside, and they can't even imagine a real solution that lacks that kind of big downside.
Your question is kind of vague. Yelp, TripAdviser, Angie's List, GetSatisfaction, and a few others all field both customer complaints and compliments for B2C businesses and even B2B businesses.