Here's the ideas I had only posted in the maplantis thread:
Water-gathering: Its basically the same as my tree cutting idea, except instead of a burrowed unit being at a tree, it is placed near some water.
Vines: On the jungle tileset, place a bunch of trees and bushes in one big compact area. If a player moves through that area, he will randomly stop(via order trigger) in mid-movement as he walks within the area. Every time the player's unit stops, there will be a kakaru death above his unit, to make it look like the player's unit stopped to cut through some vines.
Bear Trap: If a player's unit is walking through grass, there is a random chance that the player will step in a "Bear Trap". When this happens, a kakaru death happens above the player's unit. Then a mine(allied) appears below his/her unit. As long as the mine is underneath the player's unit, then his/her unit can not move away from it. This will no longer take effect when the player manages to use his/her unit to attack and kill the mine.
Terrain WAVs: Depending on the terrain your unit is walking on, you will regularly hear a specific WAV file as you walk through that terrain. For example, if your unit is walking on raised jungle, the player could regularly hear a WAV file that sounds like jungle animal noises.
Slippery Ice: When your unit is walking on ice terrain, and you order him to move a different direction, the unit will sorta "slide" and continue moving the same direction for a short moment before changing directions. This would probably involve using mobile grids to trigger this.
Blizzard: (For Snow/Ice tileset) When your character is walking through the snow, "blizzards" will randomly pass your character by.
When a blizzard happens, a swarm of invisible observers will be created somewhere nearby. Then the observers will be ordered to move past your character. When the observers are moving over your character, continiously move a burrowed unit under your character. This will slow your character down. You can also play a blizzard sounding WAV file while this is happening. This will resemble your character slowly moving against the force of a strong blizzard.
When the observers are no longer over your character, remove the burrowed unit. Once the observers are far from your character, remove the observers.
None.