On the KeeperFX website, there are almost 300 standalone maps listed, and many more maps in map packs. On this forum there is also a map list and a subforum. Dungeon Keeper is a game that's still played over 15 years after release, but it came - counting the Deeper Dungeon expansion - with a mere 35 maps.
It is good to know which of the community made maps are considered good or great, and which ones are best to be left alone. When you play a user made map, please share in this topic the name of the map(s) you played, a short description, if they were any good and why, how difficult they are, and if they have any problems.
If you want to know how to play them, take a look at the wiki.