With her pooch in tow, the Gossip Girl star celebrates her 21st b-day on the New York City set of her show. Plus: Ashlee Simpson, Lindsay Lohan, Paris Hilton and more

SUN BLOCK

Paris Hilton comes prepared for her day in the sun! The heiress keeps her cool while debuting her latest business venture – a hair extension headband called The Bandit – during a party Saturday at a private house in Malibu.