For some reason, THQ is still pumping out Saints Row: The Third downloadable content. This time, the DLC will add Penthouse Pets Nikki Benz, Justine Joli, Ryan Keely, and Heather Vandeven. The Pets will join your gang and can be summoned to fight alongside you in battles.
So yeah, new DLC. Nevermind the fact that Saints Row: The Third is pointless to play once you've beaten all the story stuff. Or the fact that you can just recreate the Pets through the character creation feature. But hey, if you have $3 to burn on pointless stuff then you can get the new content starting today for the PlayStation 3, Xbox 360, and on PC/Steam.
At this point, though, I think you should just wait for the Game of the Year edition that's bound to happen. Or save your money for Saints Row: The Third - Enter The Dominatrix.