U6Edit
Produced by: Paul Gilbert
Website: U6Edit @ Sourceforge
A powerful, Python-based editing toolkit for Ultima 6.
This powerful editing suite for Ultima 6 allows for the modification of the original game’s maps and graphics, and also includes a complete editing suite for conversations. (You may wish to refer to these Ultima 6 technical documents as you attempt to work with the Ultima 6 usecode!)
Currently, the program seems to support both Ultima 6 and Martian Dreams (but not, apparently, Savage Empire).