A collection of articles from the Virtual Beit Midrash, on halakha, philosophy, and the background of the Passover holiday. Mostly advanced material. http://www.vbm-torah.org/pesach.htm
Aish HaTorah Pesach site. Includes complete Haggada with translation and commentaries, How To Clean for Pesach, insights, and a section in Spanish. http://www.aish.edu/calendar/pesach/index.htm
Miriam's Cup honors the role of Miriam the Prophetess in the Exodus and highlights the contributions of women to Jewish culture, past and present. http://www.miriamscup.com
History and meaning of passover, including recipes, traditions, foods, symbols, art, and a translation into French. Includes passover from a rabbi's perspective. http://www.angelfire.com/pa2/passover
How to celebrate, say, pray, learn and eat on Passover; plus printable haggadah text, multi-level study, recipes, games, audio songs, stories, find-a-seder, and sell-your-chametz. http://www.chabad.org/holidays/passover/default.asp