How many times does this happen to you: You see a health/armor/ammo drop but you're too full to take it so yo plan to come back for it later. Later when you need it you're thinking, "Ok, where were all those drops I skipped?" You can mark them on your map with the built-in markers, but you only get 10 of them, and they're just numbers, you have to remember which number marks which loot, and you can't clear a single one off without clearing them all.
Also: You find a locked door, you think you remember seeing the key somewhere - did you forget to pick it up? Where was that?
Here is Loot Markers. It is a mod that automatically marks loot drops on your map and clears them when you pick it up.
Tested with Doom/2, Heretic, Hexen, Chex, Strife, and a handful of add-ons. Shouldn't conflict with other mods because it's pretty simple.
Spoiler:Items are marked when the player sees them. When an item is moved, the mark location is updated only if the player sees the item moving. The mark is removed if the player sees the spot where the item used to be and the item is not there. In this way this mod is not a cheat, it doesn't allow the player to track items that aren't seen.
All inventory items are automatically marked.
This list is case sensitive, not because of my code but because the dynamic array find() function seems to be case sensitive. So if your items aren't being marked, be sure that the case matches how the item is coded.
Download it here and check map MARKTEST to see how things are marked.
For the modders and power users: a new lump called LOOTMARK contains a list of rules to tell which items get automatically marked or not. Details in this post.
Because of this the AddLootMarkerTo and DontAddLootMarkerTo in the LANGUAGE lump are no longer processed. All rules should be placed in the LOOTMARK lump.
For the casual users: Added ability to manually mark or unmark items from the map. Hold the mark key (default M) and put the cursor on the item you want marked or removed. Details in this post