JEWISH HOLIDAYS and SHABBAT
Jewish Holidays and Shabbat
Virtual Jerusalem's Guide to the Jewish Holidays
The Holidays from Aish HaTorah
The Jewish Calendar
From the OU comes this description of every holiday and a Jewish calendar for this year and the next two years.
The Shabbat Index
Produced by the OU, this site outlines the concepts of Shabbat including the melachot.
The Ultimate Shabbat Site
Laws, songs, recipes, and world wide candlelighting times, along with a hospitality database where you can locate Shabbat hospitality by city or country.