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.
Quick! Get Creative!
Ran across this little tidbit at Creative Passionate Users: