Whenever the positive impact of religion on society is questioned, the religious often mention charity work. They send people to foreign countries (to help build churches or deliver bibles). They help [heterosexual] homeless people. They run soup kitchens. It's all just so wonderful. But charity can easily be done without religious motivation, and it often is. Many secular charities exist, and they do great work without trying to please a sky daddy or pantheon of sky daddies and sky mommies.
VBB help volunteer groups like the Humanists of Houston find volunteer opportunities in their local areas. They have a level system for benefiting groups that do charity work, and the levels depend on the number of events that are set up in a year.
DWB goes out to countries all over the world and give free health care to those who need it. Many well known atheists on Youtube promote and work with Doctors Without Borders.
AI is dedicated to fighting human rights violations and is unaffiliated with any political or religious organization. It holds governments most responsible for protecting people's rights, which is certainly a big job given the track record of governments throughout recorded history.
UNICEF is all about helping children who are the victims of poverty, disease, discrimination, violence, and having to go to bed when they're not tired. Actually, they don't do anything about children's bedtimes, but they've become well known by recruiting costumed children collecting candy on Halloween to collect donations, an activity that occasionally keeps kids up past their bedtimes.
Anyone interested in getting involved with any or all of these organizations or donating can find information on their websites. It's about more than showing that one doesn't have to be religious to be charitable. It's about people getting together to help each other simply because it's the right thing to do.