Justin Timberlake followed through on a promise to take a Marine to her unit\'s annual ball.The singer and actor posted a photo along with a letter on his website on Sunday that the Marine Corps Ball in Richmond, Virginia, was \"one of the most moving evenings I\'ve ever had\".Cpl. Kelsey De Santis had invited Timberlake through a YouTube video to Saturday night\'s event and Timberlake accepted. WTVR-TV (http://bit.ly/uD4sKV) reports Timberlake wore a tuxedo to the ball at the Greater Richmond Convention Centre.Timberlake\'s Friends With Benefits co-star, Mila Kunis, earlier this year accepted a similar invitation to a Marine Corps Ball in North Carolina.