Yom Kippur is a most significant and holy day in the Jewish calendar. Even if they don't observe other holidays and rites, many folk will put aside all work, fast, and attend services on this day of demonstrating repentence and making amends to God.
The "Judaism 101" WebSite has a brief audio clip that plays a portion of the "Kol Nidre" prayer, which forms part of the traditional evening service that begins Yom Kippur. Click here to listen to the clip.
Here is a Jewish meditation for use on Yom Kippur:
Compassionate God, let the promise be fulfilled: "I will bring peace to the land; you shall be serene and unafraid. I will rid the land of vicious beasts, and the sword of war shall be set aside. They shall beat their swords into plowshares, and their spears into pruning-hooks; nation shall not lift up sword against nation, nor ever again shall they train for war. Justice shall roll down like waters, righteousness as a mighty stream."