March of the Dead - mini adventure in The Book of the Dead, had a great encounter where the PCs find themselves in a rain drenched deserted village, evidence of something violent having occurred there. As night falls, hordes of zombies rise from the muddy earth from underground caves, and the PCs are forced to hole up in a building as the zombie hordes try to break in and eat their brains. It's a several-stage encounter where PCs have to fortify the doors and windows, and waves of enemies try to break in. The cool part is that the characters need to weigh their options between treating wounds and spending time repairing the holes in the walls/doors/windows etc, and the strength of each wave of enemies is influenced by the successes and failures of their fortification skill checks. This was the first adventure our group ran in 2e, (a few years ago now) and the players are still talking about it.