LAST WEEK in New York City, Dikembe Mutombo (below) was a guest at the premiere of Ben Affleck's Gimme Shelter, a documentary short about the war-ravaged Democratic Republic of the Congo, Mutombo's native country. The NBA All-Star and the actor hope to raise awareness about the suffering of the Congolese. Their bond could become even stronger if, as is rumored, Mutombo returns to the NBA to play for Affleck's beloved Celtics. "I told [Affleck] that I might play in his hometown," Mutombo, 42, said. "He said, 'Come, we'd love to have you.' He's a really nice guy." ... Kerry Collins has led the Titans to the AFC South title, but he wants to do more in the Music City. He wants to write a hit country song. "I am a songwriter who has a little hobby, a second career," said Collins, who recently started a music publishing company. "It's something that creates balance for me."