I have done the same things that many people have noted in this thread. Dont try to get an idea, just get in a habit of looking at things and analyze if there is a better way to do it and if there are people willing to use your solution to the idea.

I was in tokyo last month on their bullet trains and suddenly this thing came to my mind that why dont I have a bullet train in States. My iphone is my note book, I keep writing stuff in it whenever I have an idea and in the end it goes to my blog from where I choose the best one I think and start developing it. Some of the ideas are here http://nsingh.posterous.com/steal-these-ideas and if you look they are mostly random things that we come across but still ignore them.

But personally I still think that you have to go out of your comfort zone to get different ideas to work on.