Author of Snow Crash, Cryptonomicon and other geeky tomes Neal Stephenson described how he wrote his first book at a 2003 USENIX keynote speech. After an editor accepted his book proposal, Stephenson had to complete the manuscript quickly:
With all his vacation time and the 4th of July holiday there were 10 days, in which to write a novel. He rented a modern typewriter, secluded himself in his apartment and started to type. Soon a problem appeared: the typewriter had a modern plastic ribbon. The plastic mellowed and became sticky: it was July in Iowa City, and the apartment was hot. The only way to prevent the ribbon from getting stuck is to keep the ribbon moving. And the only way to keep the ribbon moving is to keep pressing the keys.
That discovery did wonders for his productivity. He didn't have time to think: he had to keep pressing the keys and write the first thing that came into his mind.
Twenty years later not many of us are tapping away on old school typewriters, but this is still a pretty great story of productivity by necessity.