Celebrities got into the Memorial Day spirit when they stopped by producer Joel Silver's annual Memorial Day Malibu beach party yesterday. Guests included Diane Kruger and Joshua Jackson, Gwen Stefani and her family, Sean Penn, Kate Beckinsale, and Tobey Maguire, who was back in family mode after wrapping up a whirlwind world press tour for The Great Gatsby. The group partied at Joel's Malibu home, which included a giant inflatable slide that was set up right on the beach to keep the kids entertained. Joel's annual party has become a major event for Hollywood's biggest celebrities — past guests have included Selena Gomez, Courteney Cox, and Tom Cruise. While Joel's party drew out a ton of A-listers, that doesn't mean that they were the only stars who were celebrating over the holiday weekend — check out how the stars celebrated Memorial Day!