For what I know...
1. WI Hitler had been killed on July of 1944? (there were also major plots and attempts in 1943, 1941, 1939, 1938 and a car accident in 1930)
2. WI Operation Michael had been successful?
3. What if the Archduke had not been shot?
4. What if Richard Nixon had won in 1960?
5. What if Robert/John Kennedy had not been killed?
6. What if Stalingrad/El Alamein/ Britain, etc...had been German victories?
7. What if President Huey Long? (or any other politician from Ross Perot to Joe McCarthy)
8. What if Cold war hot?
9.What if Enoch Powell, Michael Foot, blah, blah...oh, and Labour Victory in 1982?
10. What if Argentina...well, that's not exactly popular, but I'm trying and many of the newbs trying to avoid the cliche WWII introductory thread think that using Argentina will make them look more original...
Also, things like Korea, the Abyssinian war, Cambodia, the Italo-Turkish war, early Israeli history, Japan before 1914 or the Far East after 1945 don't seem to attract too much attention...