I can think of a ton of superstitions just off the top of my head.
Ones which bring bad luck: walking under ladders, breaking mirror bringing 7 years of misery, black cats crossing your paths, opening umbrellas inside, and, according to my friend, masturbating giving you hairy palms (never heard that one before.)
Ones which bring good luck, or prevent bad luck from occuring: knocking on wood, or as Italians say, "toccare ferro": to touch iron. Throwing salt over your shoulder, finding horseshoes or four leaf clovers all supposedly bring good luck.
One tradition/folk remedy that sticks out to me above all though is eating chicken soup when you're sick. We're Jewish and my dad always likes to refer to it as "Jewish penicillin." I've never actually googled or looked into it, so imagine my surprise when this was the first thing that popped up in google search: http://www.jewishpenicillin.com/ with the lovely header "Healing the world, one bowl at a time". Right on the front page is a claim by some random doctor who no one has ever heard of saying chicken soup actually has "mild medicial effects." Who are you, Dr. Random Stephen Rennard? With a little more clicking around, it looks like the site is just a fundraising organization. No dice. Wikipedia sent me to a NY times blog. http://well.blogs.nytimes.com/2007/10/12/the-science-of-chicken-soup/
Lo and behold, Dr. Rennard was mentioned again. He works out of the University of Nebraska Medical center in Omaha. His study -theorizes- that the soup acts as an antinflammatory. Researchers took up his challenge and did some studies of their own, comparing the effects of hot water and chicken soup, only to find inconclusive results overall.
So is chicken soup the cure all, end all of sickness? Not exactly.. but there is no research claming it does any harm. As long as it is somewhat healthy and makes you feel good, placebo effect or not, chicken soup is, relatively, good for the soul.