Here are a few worthy causes:
http://www.pajamaprogram.org/ - provides pajamas to children in shelters
http://www.garden.org/ - provides seeds for vegetable gardens to feed families
http://www.savethechildren.org/ - provides life-saving medication to children
http://www.plasticjungle.com/ - turns gift cards you won't use into donations to your favorite charity
http://www.doctorswithoutborders.org/ - provides vaccinations against life-threatening illnesses
http://www.smallcanbebig.org/ - provides help with bills (electricity etc.) to families in need
http://www.theirc.org/ - provides winter coats to refugee children in the U.S.
http://www.gocampaign.org/ - provides food and necessities for children in developing nations
http://www.fistulafoundation.org/ - helps women recover after debilitating childbirth
http://www.feedamerica.org/ - provides food to hungry families in the U.S.
http://www.imcworldwide.org/ - provides health care to survivors of sexual trauma