I see companies like Fiverr.com making huge profits powering micro entrepreneurs. I have an idea of launching a website that uses people from Pakistan to see a website for 15-20 seconds and tell them what he feels about the site, how it could be improved and what issues he faced on it. For $5, 20 people will review the website and the user will get 20 suggestions. I can find the people and make the site. I am thinking what would be the value of it for people around the world?
Test it on fiverr. Then you'll know.
If my product a targeting US or Western Europe and I get feedback from someone from Pakistan how he feels about it is not really useful for me as there are cultural differences. Something felt negative about in Pakistan might be positive in Europe.
If you have a network of people thorughout the world - crowdworkers - doing it that might help coz I want to specify the target audience I get felt feedback from.
If it would be about usability issues then it would help but that requires tasks to be done and those will take more than 15-20 seconds. This goes more into usertesting.com