On a serious note, an interesting POD would be some kind of viral outbreak occuring in Vienna in 1913 and killing them all.
Perhaps the scariest notion is a more competent, pragmatic man coming to lead the Nazi movement.
Freud had already done much of his work, but had yet attain the major mainstream recognition he would attain. Perhaps Jung would replace him as the public face of psychology. In any case, a less famous Freud has massive, massive butterflies; since basically the entirety of the public's perception of psychology (id, ego, superego; conscious mind vs. subconscious; repressed memories; Oedipal complexes; etc.) is straight from Freud.
Trotsky and Stalin both dying in 1913 has enough butterflies (and I have insufficient knowledge) that I can't really comment on the implications. Same with Tito, I just don't know enough about the man.
