I think that what people need to be really creative are spaces -- like "comfort food" for the mind -- it's not just the taste, but the sight, the smell, the texture, and possibly the context of the surroundings. Perfect example? Your basic American Thanksgiving Day Dinner!
I actually find that I can really focus in the middle of a noisy coffee shop -- or when I'm working on software I need to have super high energy EuroTrash music pumping out like the stuff you find at Digitally Imported (it's a guilty pleasure I know) -- in other words find a physical as well as a mental space that supports you. (for some reason sitting in the confined space of an airplane seat I suddenly get the urge to write/ideate -- it's the "limited resources" principal at work -- and also akin to the old addage "to make good wine you have to stress the grape a little")
When I was in Japan I spent hundreds of hours in a coffee shop near my office that always had classic jazz playing in the background -- the constant hiss of the espresso machine, the din of the daily crowd coming and going, and the background noise of a foreign language provided a lot of brain candy. I look back now at the journals I kept and am amazed at the shear volume of ideas and designs I produced in that era!
Getting creative requires the same kind of time and attention to context -- which is why I agree with Dave that having a space both physically and mentally are critical to consistent inspiration. Stock it with the kind of tools and distractions you need to feed the muse.
So, Today's Other Big Idea is this: Being creative sometimes means not focusing but unfocusing