The consensus seems to be that if you want to make money from a blog, you need to find a niche, or “nitch,” as some of our American cousins so amusingly call it. 
What is a niche? The dictionary definition of a niche is:
“A special area of demand for a product or service.”
Now that’s a fairly broad definition and perhaps the wikipedia definition is more enlightening: “By definition, then, a business that focuses on a niche market is addressing a need for a product or service that is not being addressed by mainstream providers. A niche market may be thought of as a narrowly defined group of potential customers.
A distinct niche market usually evolves when a potential demand for a product or service is not met by any supply, or when a new demand arises due to changes in society, technology, or the general environment.”
A blog devoted to “Interesting cornflakes shaped like a country in South America,” could be one such niche, but I very much doubt there will be a great deal of interest in a blog about cornflakes, so unless you have a special relationship with Kelloggs, it’s unlikely to prove a very profitable niche.
The problem, of course, is that everyone is trying to address a particular “niche,” which of course means – it is no longer a niche market. This blog is a niche blog, or was when it started. A blog about blogging. There are now any number of blogs about blogging – none of them as good as this one of course. 
So, how do you go about defining your niche and then making it profitable. As I have spoken of before, trying to write a niche blog on a subject you have no interest in or knowledge of is likely to end in tears. Or at least, yet another abandoned blog. Here are a couple of “niche,” blogs that I write:
International Property Investment
One of them reasonable well established, the other a new one. Luxury Property is much more of a niche than Property Investing.
So, what is your “nitch,”? How did you decide on that particular niche, and why is it successful for you?
My nitche is "Latinamericans immigrants in Canada and Latinamericans in their way to Canada as inmigrants" Someone described my blog a few days a go as "a blog devoted to the positivist, latinamerican professional in his/her way to Canada as an Immigrant" It was not that bad.
It works for me because it lets me merge my passions: writing and helping others. And although is not a huge market, 20k+ potential immigrants every year is good enough for me.
One of my sites is a Macrobiotic site.
Not a huge market but combined with green tea awareness and laws of attraction-it's a one stop shop for those three interactive interests.
My "nitch" is Beer and wine, specifically in homebrewing. I found the niche, because I'm a part of that niche. I'm a homebrewer. It was slow at first, but I think over the past 6 months the blog is finally starting to grow.
Some interesting "nitch" sites here then. I especially like the homebrewing one.
My site can be loosely defined as a "second page" news. The biggest and most important news are splashed all over the front pages, discussed everywhere and are difficult to miss. I write about many things, which people might need to know, but missed, because it appears on the second page or burried under the various categories. My topics are: interesting info on insurance, ID Theft, some art news, luxury items and properties, wineries, useful information and tips, some appliances and electronic products, travel…In short, info for the soul and info for the wallet.
Thanks! I'm trying to make homebrewing more popular and less of a niche.
What who is making cornflakes the shape of South America, I want in lol. You have some very valid things to say there. The one thing to remember is High Demand/Low Supply. Find those undiscovered niches or even a niche within a niche and capitalize on that. I currently have 24 hot new niche products on offer just click on my name.