Hilary Duff brought little Luca Comrie over to a friend's house for a playdate in Beverly Hills yesterday. The mother-of-one balanced a stylish Céline bag and her baby boy Luca in her arms as she crossed a grassy lawn in a pair of Rag and Bone booties. While those shoes are getting put to good use, some of Hilary's other pairs are being put towards a good cause. Several pairs of Hilary's autographed heels were put up for auction on Ebay recently, and she promoted the listings on Twitter with the hashtag #KickUpYourHeels. Money raised from the fundraiser will help support children's workshops and programs at the Lancaster Opera House Theatre in New York. Other celebrities getting on board include Kelly Clarkson, Brittany Snow, and Ashlee and Jessica Simpson.