Southwest Airlines is a supporter of Kidd's Kids, a Texas-based organization that provides vacation adventures to medically-challenged children and their families. In recent years, this has been an all-expense-paid trip to Disney World in Florida. The group was started in 1991 by Dallas radio personality Kidd Kraddick after he used his radio show to raise money to replace a little girl's stolen wheelchair.
Kid's Horizons is an Air Canada program that provides transportation to children who need medical care that is not available in their community. The program is supported in part by donations of frequent flier miles.
American Airlines is a corporate sponsor of Susan G. Komen for the Cure, one of the world's largest breast cancer research organizations. This B777 is one of several aircraft that American has decorated with pink ribbons.
Delta Airlines has been a supporter of the Breast Cancer Research Foundation since 2005. Each October, in recognition of Breast Cancer Awareness Month, Delta offers pink lemonade on their flights, with proceeds going to the BCRF.
Alaska Airlines has been a supporter of the Make-A-Wish Foundation for over two decades. Make-a-Wish grants wishes to children with life-threatening medical conditions. This B734 features the genie from the Disney movie Aladdin, and is called the "Spirit of Make-a-Wish".
American Eagle has also been a supporter of Make-A-Wish; this specially-painted ERJ was dedicated in 2001, and features artwork by four Make-A-Wish kids. I haven't seen this one in some time, and it may have been repainted. Here's a better picture by someone else.
Delta Airlines is also a supporter of Habitat for Humanity. Former president Jimmy Carter has brought Habitat to the awareness of people world wide. Habitat works to reduce homelessness by providing homes in partnership with the families who will live in them.