Holy days provide us with a beyond-the-everyday opportunity to reflect in celebration or in solemnity upon the season. Earth Day is the first holy day which transcends all faiths and traditions, and so you may wish to anchor your environmental calendar in the spring.
Advent and Ecology Liturgy
http://www.arcworld.org/faiths.asp?pageID=78
Canfei Nesharim: Holy Days
http://canfeinesharim.org/learning/make_difference.php
Celebrating and Caring for God’s Creation
http://www.pcusa.org/peacemaking/worship/earthday09.pdf
Coalition on the Environment and Jewish Life: Celebrate
http://www.coejl.org/celebrate/
Earth Day Liturgy from the NCC
http://www.beliefnet.com/Faiths/Christianity/2001/04/Earth-Day-Liturgy-From-The-National-Council-Of-Churches.aspx
Earth Ministry: The Liturgical Year
http://www.earthministry.org/resources/worship-aids/liturgical-year
Season of Creation
http://www.earthministry.org/resources/worship-aids/liturgical-year
The Shalom Center: Celebrations
http://www.shalomctr.org/taxonomy_menu/1/126
Sukkot: Season of Gathering and Giving
http://urj.org/_kd/Items/actions.cfm?action=Show&item_id=4446&destination=ShowItem