Many of these niches that were mentioned are huge markets. So, I assume everybody means some sector of health, or real estate, etc. Not a Health site. Ok, so based on that, pick one of those markets. Say Health. Go and use a keyword tool and a synonym tool and find some more 'niche' specific key phrases that might help you get a real niche site. Just plug in the most broad keyword and let the tool go to work for you. Then select something in that list and research it some more by finding out how many pages are in google for that term and how many people are searching for it.
I think I will agree with animatedmarketing, Health is too broad... I forgot to mention when I mention Health alone... you can pick ACNE as your topic, this is a widely searched keyword for example... so kindly find the best segment of health that you are interested in and focus on it...
Hey friend, For me the work making a passive income or working at home is popular as recession is now here and a lot of people are jobless.
Making money online - forums like this one are pulling in good money. Job/work related websites are also doing well...