I was reading about this business that was kind of unique as instead of offering its services during the daytime like many in his field he offers them during the graveyard hours. As you may expect, he capitalizes on people that need sudden emergency services at night time. Not surprisingly, while it may not be much in terms of the whole market in general, he gets virtually the whole pie here and therefore makes a decent living out of it.
This is one of those choices that would definitely affect your whole lifestyle in general. Example, you have to become a night owl to do this. But what it does show is that there are certainly a lot of variables to choose from when it comes to attracting business to make a living.