Over the years, a lot of good editors have been made for various games. In particular, the Gold Box games have some good editors and automappers:

Quick note on Eye of the Beholder trilogy:
There are two (freeware) automapper utilities for this trilogy. All Seeing Eye for EoB1 and EoB2. All Seeing Eye 3 for EoB3. Links are:
http://ase.zorbus.net/
http://ase3.zorbus.net/

Jonas H's approach is based upon DosBox, neither of the ASE programs will work without the relevant EoB# game being played with DosBox.

There are articles on the trilogy too:
Eye of the Beholder III Hub
http://ua.reonis.com/index.php?topic=3417.0

Automapper Utility for Eye of the Beholder 1 & 2
http://ua.reonis.com/index.php?topic=3423.0

For other Gold Box games, there is the Gold Box Companion...
http://gbc.zorbus.net/

UGE - FRUA Hacking
http://ua.reonis.com/index.php?topic=2404.0
This deals with the Universal Game Editor.
Generally UGE will be inferior to an editor created specifically for a given game or series.

Attached image: All Seeing Eye in action