Now lets break that down
Halo -> A multiplayer game made by bungie
Memory -> A unit of a computer that preserves data for retrieval or Capacity for storing information
Editor -> Something that makes changes to something
Now all combined this would imply that this application Edits the memory of a halo game.
Crazy, rite? .....rite?
Features
-Dependency swapper
-Plugin run meta editor
-extract/inject meta
-load map from memory (no need close app to load a new map, just hit load map agian)
-save map from memory with support of physical file
-Sheer awesomeness of real time modding

Now heres a download