At times, a horseshoe may be found above doorways. When positioned like a regular 'U' it supposedly collects luck. However, when it is positioned like an upside-down 'U' the luck supposedly drains.
The superstitious symbolism of a black cat crossing one's path is dependent upon culture: some cultures consider this a sign of impending bad luck, while some cultures consider this a sign of impending good luck.
Breaking a mirror is said to bring bad luck for 7 years. To "undo" this, take the shards of glass and bury them underneath the moonlight. In ancient times, the mirror was said to be a window to the viewer's soul. If that mirror were to break, it would
If one walks underneath an open ladder it is said to bring bad luck. Sometimes it is said that this can be undone by immediately walking backwards back underneath the ladder.
Opening an umbrella indoors is said to result in 21 days of bad luck. Some traditions hold that it is only bad luck if the umbrella is placed over the head of someone while indoors.
Placing a hat on the bed is, apparently, bad luck. (South Carolina)
Placing keys on a table is considered unlucky. (Sweden)
It is bad luck to put new shoes on a bed (or a table) (comes from the tradition of dressing a corpse in new clothes and shoes and laying them out so everyone can give their respects) - (UK)