Even the most fashion-forward luxie likes to dress down once in a while. Make the most of your casual Friday by rocking a tee that's stylish -- while helping a great cause!

Gift Horse A portion of the proceeds from Ralph Lauren's Pink Pony collection go toward the Pink Pony Fund for Cancer Care and Prevention.

Pink Pony Slim-fit Tee, $98

Make a Marc Marc Jacobs, er, titillated the fashion world with his tees featuring nude celebs, raising awareness for skin cancer -- and almost $400,000 for the NYU Cancer Institute.

Marc Jacobs NYU Cancer Institute T-Shirt, $35

ONE More Tee Edun, the ultra-hip and socially-conscious clothing company founded by Bono, wife Ali Hewson and New York fashion designer Rowan Gregory, has designed a T-shirt for the ONE campaign to eradicate poverty around the world.

Edun ONE T-Shirt, $40

Red Hot Julia Roberts teamed with pal Georgio Armani to design this shirt for the (Product) Red campaign. A percentage of the profits from all Red products go toward buying and distributing antiviral medicine for those suffering from AIDS in Africa.

Emporio Armani (Product) Red Julia Roberts T-Shirt, $125