As soon as I read the title of this thread, I thought of an article I once read on Steve Pavlina's blog called
"10 Reasons You Should Never Get a Job". It would be the ultimate to have a website that generated revenue 24/7 whether you were "working" or not. Obviously, if this were easy to pull off, everyone would be doing it... but the idea of not having to trade your time for money in some sort of predetermined ratio really appeals to me.
I think that if anyone is going to start a small business or try to support themselves without a traditional job (whether you're consulting, creating art/music, making furniture in your garage, or writing a blog), you need to find a niche. Focus on one specific problem or need and figure out how to solve it and make money from it.
Even huge successful companies started with one idea that they did exceptionally well and then built on that. Google is a great example... they focused only on making their search engine the best, then expanded and developed other products like maps, email, photo sharing, etc. and integrated all of them together.