Actress Marlo Thomas is urging shoppers to swap their pre-Christmas purchases for a donation to charity. The That Girl star is a vocal supporter of St. Jude Children's Research Hospital in Memphis, Tennessee, which was set up by her late father Danny Thomas, who died in 1991. And Thomas, 67, hopes people will give generously to good causes during the holiday season. She says, "So many moms and dads come up to me and say that their child wouldn't be alive if it wasn't for St. Jude. Not just because of the research that we're doing there, but because they couldn't have afforded it. "When people go out shopping, they should look for the green magnifying glass. It signifies that we never stop looking for cures. And when the associate at the store says, 'Would you like to add something for the kids at St. Jude?' add something. Add $1, add $2. Add whatever you can afford,"