I consider it a mark of shame that religious folk donate more money to charity than secularists. That's one of the reasons I bug the hell out of everyone who will listen about donating money to Donors Choose. I've recently been looking into other secular charities that have a bit of a broader scope. That being said, a lot of secular charities seem to exist to perpetuate secularism rather than actually render services to those in need, which is frankly one of the concerns I have about religious charities. I want my money to go to people in need, not to proselytize about belief-systems - even if its one I agree with.
Sure, I agree in general with groups like the ACLU, but there's an extent to which I'd rather fund direct services like food and educational aid rather than give money to fight over esoteric, if often important, legal issues. With that in mind, here's a list of secular charities that do provide direct services that may be worth looking into for folks who want to donate some of their resources to the less fortunate.
UNICEF - The United Nations World Children's Fund. UNICEF provides everything from food and vaccinations to educational services and is also at the forefront of the battle against HIV/AIDS in Africa.
Second Harvest - Second Harvest is the largest food bank in the United States and provides emergency food aid to disaster victims throughout the USA and Canada.
S.H.A.R.E. - Secular Humanist Aid and Relief Efforts. Paul Kurtz's secular charitable organzation, S.H.A.R.E., provides emergency aid to disaster victims and helped to alleviate some of the suffering doled out by the recent Indonesian tsunami and Hurricane Katrina. Some of you may recognize Kurtz as the found of the Committee for Skeptical Inquiry.
I'll continue to post info on other secular charities as I get the chance to do so.