How about a place where all of the inhabitants were neutral or good but have been made undead without realizing they are undead.
The thing that makes it fun is you have people working the fields, selling (rotten or mummified) bread, gossiping with each other, etc. They would even beg for their lives if threatened. Could be an interesting role-playing experience. What if it could be proven to them they are undead?
The leader of the place might be evil, or he/she might have been swept up in the same force that converted the others.
To let the people find rest in death, the party would have to reverse the magic that made it possible (or just kill them all I guess). Maybe a powerful Lich did this deliberately, or even better it was a side-effect of another spell.