This mod will show all the monsters on your automap. You will see the crosses and the monster name in text on your map. Unique monsters appear in red, so you can easily spot them. Bosses do not appear on map. Only flaw is, monsters have no life bar, and you can't see their stats. That shouldn't be a problem until hell unless you already know what's immune to you.

This works great with reveal map.

http://d2sector.net/downloads/gallery//show_monsters_on_map.jpg

Download:
Show Monsters On Automap (http://d2sector.net/downloads/index.php?dlid=179)

Interesting. How does it work? Is it a mere mod or is it some kind of plugin? I hope I'm making sense - damn rusty on the terminology.

All this is, is a mod. This can easily be done, by just editing one file.