Today is the Jewish Day of Atonement. Here is a website that tells you all about our customs.
Yom Kippur Central. Check it out. Here are some highlights:

When the High Priest emerged from the Holy of Holies unharmed, having successfully achieved atonement for the people, he would offer a moving prayer for them. First he wished them a year filled with all the blessings of G-d and later he would prepare a celebration to thank the Almighty for allowing him to complete his monumental task.
-- From the Yom Kippur Service

An Overview of Yom Kippur The Customs of Erev Yom Kippur The Prayers of Yom Kippur The High Priest's Temple Service Torah Readings On Yom Kippur
The Shofar of Elul and the Days of Awe
Yom Kippur Stories
Kol Nidrei NightRav Yaacov Haber
Breaking Heavenly BarriersRav Yaacov Haber
Rav Avi Weiss on Yom Kippur '58 Rav Shlomo Riskin on Yom Kippur
The ABCs of Yom KippurAish HaTorah
Exploring the Al-Chet PrayerAish HaTorah
LES YAMIM NORAIIMPar Le Merkaz Sepharade
Yossi & Co. On Yom KippurFor the Kids by Ohr Somayach
Yom Kippur Q&AOhr Somayach
Book of Yonah Q&AOhr Somayach