Redtom,
For starters, if you're into Science Fiction take a read of Robert Harris' 1992 book *Fatherland*. The story begins in the early 1960s - twenty years after the Nazi's great triumph - and only now is the Third Reich with its aging Führer attempting to re-establish relations with its former defeated foe, the United States. The U.S. was victorious against the Japanese but the invasion at Normandy in 1944 was repelled; Britain was overrun (Churchill just barely escaped to Canada) as was Moscow. The Soviets continue a guerilla war east of the Urals, but this is a minor annoyance. President Joseph Kennedy - I said Joseph, not John - is coming to Berlin for the first visit of an American President since the war to re-establish relations.
I won't spoil the story for you but what's interesting is that because World War II ended earlier and the British were overrun relatively early, technology didn't play as important a role in the world that we know today. Television had been invented but was not widespread in the 1960s yet in the book (vaccuum tubes from planes in WW II solved a size problem on early TV sets that made them widely accessible). Harris describes several consumer and civilian technologies that we know happened in real life but in Harris' world didn't because the war ended so lop-sidedly in a German victory.
Several posters on this thread have already mentioned excellent examples of war-driven technology so I'll give you a synapsis:
With the French Revolutionary and Napoleonic wars in 1795-1815, the French introduced leveé en masse that brought nearly the entire adult population into the war effort. In that short time armies went from being small professional forces to huge, unwieldy armies. This proved that merely having greater numbers didn't guarantee a victory. In fact, if you had a competent commander, he could usually defeat larger forces with smaller but well-trained and flexible forces. However again, not every commander is a Napoleon; most are average and some much less than that. That left one area to turn to for advantage: technology.
Technology has been used in wars for as long as humans have fought one another, but not until the 19th century did technology achieve such focus and attention. The Industrial Revolution that started in Britain and France spread throughout Europe and North America gradually, and created a powerful impetus for technological change in warfare. In the Crimean War, the British used a kind of pressed rubber and oil to make macintoshes for their freezing troops outside Sevastopol (that ultimately led to the discovery of vulcanization and modern tires), and the loss of a supply ship to a storm forced the British to develop the first comprehensive weather forecast system. The American Civil War saw the introduction of the iron-clad ships, practical submarines, paper-cartridge rifles, effective use of the railroad to quickly transport troops around, and portable cameras. The Austro-Prussian War revealed the progress of artillery that made fortresses obsolete (see Klodzko, Poland) while the Franco-Prussian War saw observation balloons.
The real show began in 1914, however, with both sides racing to invent new technologies that could break the deadlock of the Western front. Canned foods (preserved soldiers' rations), more efficient plane engines, barbed wire, wireless communications (hello radio), popular music (the spread and influence of many popular styles as soldiers from around the world mingled, but especially American "ragtime", that assimilated into proto-jazz, rock, etc.), audio-recording technology, more powerful land vehicle engines, more sophisticated diving technology (to lay/remove mines, recover wrecks), a vastly better understanding of human hygiene (one of the first major conflicts where more men died from enemy bullets than disease in the camps), improved "triage"/trauma medical expertise (I survived an ugly car accident years ago because of that technology; thank you!), HUGE advances in chemistry, astronomy (navigation), mechanical physics and geology - all either invented in or vastly improved upon by the experience of the First World War, and paid for with the blood of 10-12 million soldiers.
World War II brought even more, almost innumerable. The invention of the radial engine, the diving gas tank, mass media, the radio, vaccuum tubes and transistor crystals, radar, rocket & jet technology, and others that have already been mentioned.
As a final example, let me follow a technological string for a moment: In the early 19th century Europe was very into Indian, Persian, Afghan, etc. rugs and blankets; very fashionable. The problem was it took months or even years to complete some of the nicer and more complex designs, so a Scotsman (name forgotten - I apologize) who emigrated to New England got the idea to use punched cards on looms. The loom was rigged to a card with specific holes punched in it, each hole representing a specific color thread. As the loom spun, hooks attached to the advancing loom were dragged across the card, and each time it hit a hole, it added that color thread to the design laid out by the holes in the card. In this way, a very complex and expensive-looking eastern-style rug could be made in days instead of months. Woohoo! The wooden loom was known as Hardware, and the cards became known as software. (Can you see where this is going?) Two generations later, a descendant of the obviously by-then wealthy family of the Scotsman who invented this textile technology was working in a comfortable U.S. government job, collecting the numbers for the 1900 census. He applied the technology he'd learned by using the textile cards with holes punched in them to keep data for the census; hole here meant red hair, hole there meant blonde, hole here meant blue eyes, hole there meant brown, etc. He quit his Government job and used these cards towards two practical office inventions; the typewriter and a primitive kind of calculator. He founded a company, International Business Machine, that I think is still active today... (IBM)
Taking this farther, in World War II the U.S. government needed to be able to colect and store vast quantities of intelligence and information about things going on literally all over the world. IBM used that punch-card technology to invent the first primitive data storage units, that we could call the first real computers. After the war, when the Cold War brought a new threat of world-wide confrontation, the United States needed some way of collecting and storing data about radar sites and spying technologies all over the globe to make the sure the Soviets weren't attempting a sneak-attack; and IBM came back with the answer in teh form of the first primitive networks. The Americans wanted to know in real time what the Soviets were doing all over the world, and the IBM networks were able to do this for them. These networks entered the civilian world through the newly-created airline industry, which needed to keep track of customers booking flighst from all over. That direct network links could facilitate direct communications, not just data transfers, was something the U.S. military hit on the late 1960s though this technology wouldn't catch on in the civilian world until a decade later (e-mail). Thus was born the internet and eventually the "WWW". (Only in the 1970s were the punch cards finally tossed in favor of microchips.)
So there's a story of a technology that was buffeted and developed by the necessity of war and potential war.
Hope this all helps -