I like it when time travel is handled in a more "quantum" manner. In the James P. Hogan novel "The Proteus Operation" you have an alternate universe where the Nazis acquired the atomic bomb in 1941 (by inventing time travel and using it to go to the future and steal it) then used it to bomb Russia into submission, forcing England to surrender without firing a shot. This left a mid-70's world where the only free nations left were the US, Canada, and Austrialia (however, Austrialia was about to capitulate to the Third Reich). Revolutionary element in Britian then steal the Nazi time travel technology and use it to go back to WWII-era Nazi Germany and destroy their time machine so the Nazis can't use it to steal their nuclear technology. They acomplish this mission only to learn that they didn't really travel through time, but rather, between alternate universes that exist at different points in time, so they never changed anything in their own "time" and to live in a free world, they'll have to stay where they are some 40 years prior to the time they lived in before. They do that, and pass the nuclear secrets the Nazis stole (from a very futuristic Earth, IIRC) to the United States, essentially creating the "real" world we live in. This method of "time travel" solved the problem of changing the future, but retained the weirdness of meeting the alternate universe version of yourself. The Michael Chricton novel (and movie) Timeline used a quantum model as well, but it was still traditional time travel with changing the future and stuff. Time travel was achieved by shrinking one down small enough to travel through wormholes in quantum foam. Plotwise, the story was kinda stupid, but the science was very cool.