For those that didn't play Point Lookout, the DLC adds an eerie swampland area where the player gets to see what happens to communities that didn't actually get blown up by the bombs.
ShoddyCast retells the tale behind the location, and its unsettling citizens—which are waging a war for reasons that even they can't remember. It's a great watch, even if you have played the downloadable content. Skip to the :45 mark, if you're short on time:
It's stuff like this that is getting me more and more hyped up to be replaying Fallout 3.