CheeseLab 2
This release is no longer maintained, the latest CheeseLab is CheeseLab3 which is available here. It is java based and cross platform, this page remains up for historic interest of the project only. Download last released before cheeselab3

Since everyone seems to be making mappers for MUME these days, I decided to make one too. Cheeselab is a MUME map generator/realtime mapping client. The setup tracks players and shows a graphical representation of MUME and also stores a database of notes, mobs, secrets, quests, etc. Currently unreleased, but it works. The mapper is made of 3 parts, taking ideas from both azazello and diamonium's mappers: Here's the links to other MUME mappers:
There are some pictures of the mapper below, click on them for a larger image.

This is the normal map, showing what it looks like when you move around. I am the angry blue face in the middle, the pink line to the north means I'm going to end up somewhere I can't see on the map.
Here I went north, and since the rooms overlapped with the OER to the north, I'm now under that room. You can always see what's 1 level above you so that you can have some idea where you'll pop out when you come back to the surface level.
This shows all the current child windows that are implemented, which include a movement tool to move the map around (it also has a "follow player" mode), the right-click toolbar which indicates what happens to a room when you right-click it, e.g. move it or merge it with surrounding rooms, and the infobox. The infobox shows all the room detail that's in the database, such as exits, where they go, the name/description, secrets, notes, etc.
Some rooms have been selected, once selected they can be moved around using the keyboard so that it's easy to fix places that don't match up. You just run through the zone, making sure you got all the rooms, then go idle somewhere and move around the rooms so they match if there was any overlap. Which happens quite a lot I might add.
Here the map has been zoomed in a bunch, and also shows the notes tab on the infobox. The map can be zoomed in or out, tiles are automatically resized and then cached for future use.
This is zoomed way out. You can make the tiles as small as 10x10 pixels this way. Not ideal for playing, but looks cool :)
This shows searching the database