HERE'S AN ARTICLE ON JEWISH BLESSINGS AND CURSES from the Jerusalem Post. Excerpts:

Curses can be a powerful thing and weigh heavily upon those who believe they are so afflicted. The idea of curses and blessings pervades the narratives of the Torah. Adam and Eve were cursed when they were driven out of the Garden of Eden. Cain was cursed for the murder of his brother Abel. Lemech was shunned for killing Cain, and Noah cursed Ham and Canaan for their despicable behavior toward him. Joshua cursed anyone who would dare to rebuild ancient Jericho. Elisha cursed the evil youngsters who tormented him.

However, we are taught by the rabbis of the Talmud that the power of good is 500 times greater than the power of evil, and the Torah is replete with narratives of blessings. Abraham is blessed by God and told: "Those who bless you will be blessed and those who curse you will be themselves cursed." Abraham passes on his blessings to Isaac. Jacob receives Isaac's blessing but gains Esau's enmity. The brothers of Joseph begrudge him his father's favoritism and blessing.

Blessings are often bittersweet. All of the great characters of the Bible, from Joshua through Ezra and Mordechai and Esther receive and/or bestow blessings. Blessings are a volatile matter and must be dispensed wisely. In the Torah, we are instructed to bless each other as well as the God that created us.

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The use of amulets to convey blessings is a topic of great controversy in Jewish history. There were amulets prepared for every possible blessing in life and to ward off all imaginable misfortunes. The Talmud discusses the use of these amulets in a halachic sense, such as whether they may be worn in a public area on Shabbat. From many halachic sources, it seems that the use of these amulets had a placebo effect on the people who wore them.

There were great rabbinic disputes regarding amulets, but the Jewish public, especially after the rise of Lurianic Kabbala and Hassidism, adopted their use - and they remain popular among certain sections of Jewry today. The custom of inserting a prayer into the cracks of the stones of the Western Wall is an offshoot of this tradition