Saints Row: The Third, which is for some reason also known occasionally as Saints Row 3, has had plenty of solid DLC. "Gangstas in Space" and "Trouble with Clones" come to mind, as they brought whole new storylines and missions.
In addition to that, there were a ton of random packs that brought new weapons and vehicles and other miscellany. And now there's a "Full Package" edition coming Nov. 6 (Nov. 9 internationally) that will compile them all on one disc.
It's hitting Xbox 360, PS3 and PC for $50. If Saints Row 3 has been on your list but you haven't yet purchased the game or any of its DLC, this is the perfect way to get into it.