The High Holidays with Aish 
Aish HaTorah site for Rosh HaSana and Yom Kippur. Articles, instruction, insights, plus family activities.
http://aish.com/holidays/The_High_Holidays/The Complete High Holidays
Extensive collection of articles on every aspect of the High Holidays: Elul, Rosh Hashana, Yom Kippur, Sukkot and Simchat Torah; interactive quizzes; recipes; Ask-the-Rabbi; full calendar; holiday services search. (From Chabad-Lubavitch)
http://www.chabad.org/holidays/jewishnewyear/
Rosh Hashanah and Yom Kippur
Essays, audio and the laws from the Ohr Sameach yeshiva.
http://www.ohr.org.il/yhiy.php/holidays/rosh_hashana_and_yom_kippur/
