The Objects of Supernatural

Bugs

In the Episode Bugs, the boys face a Native American curse stating that every 40 years, all the bugs in the town would attack the white men.
Episode: Bugs

Witches Canyon

In the book witches canyon there is a Curse ton the town that causes all the ghosts of the dead to return every forty years and kill the townsfolk.
Book: Witches Canyon

Cursed items

Rabbit's foot

In the episode Bad day at black rock, Sam and Dean come into the possession of a Rabbits foot. Unfortunately it is a cursed item. When you touch it, it gives you good luck. But if you lose it, you get so much bad luck that you eventually die.
Episode: Bad day at Black Rock

Hand of Glory

This hand belonged to a murderous sailor. he was hung and his hand removed to make a magical item. unfortunately the sailor would return and kill people by drowning them. Bela sold the hand to the highest bidder.
Episode: Red Sky at Morning

Ruby's knife

Ghost truck

Episode: Route 666

Symbols

The summoning sigils and the Devil's traps.

Summoning for Azazel
from In my time of dying.

Devils Trap from Key of Solomon. It can trap any low-life demon.