First off. Terrible question I know, but with all the history painting Hitler and the Nazi's as the ultimate evil it's hard to get a glimmer of the good things they did. Or just things they did well.
Not a Nazi sympathizer or trying to create any, but it strikes me as necessary for there to be something good about them or they wouldn't have gained so much power in the first place.
Robert Proctor has written a book on just this subject, The Nazi War on Caner, which shows the Nazis were decades ahead of other countries on linking the health effects of cigarette smoking and cancer. They also were ahead of the curve on asbestos, radiation, and food and occupational safety hazards. The same thinking that went into believing the Jews and other peoples were unclean also supported Nazi restrictions on other environmental toxins.