One of the best ways to be truly creative--breakthrough creative--is to be forced to go fast. Really, really, really fast. From the brain's perspective, it makes sense that extreme speed can unlock creativity. When forced to come up with something under extreme time constraints, we're forced to rely on the more intuitive, subconscious parts of our brain. The time pressure can help suppress the logical/rational/critical parts of your brain. It helps you EQ up subconscious creativity (so-called "right brain") and EQ down conscious thought ("left brain").
(One of the best ways to quickly test the dramatic power of shifting from left to right is with Betty Edwards Drawing on the right side of the brain work.)
partial post from Creating Passionate Users