Solved Level 18 as well now. 100%, three miners and a digger over.
EDIT: Solved #16. The only case in the pack so far where I feel sure my solution was harder than whatever was intended. I'd like to hear other people's solutions to this one..... here's mine:
[highlight]First lemming digs all the way down the pillar on the left. Second lemming (who is made a climber) goes past, digs down just before turning round, and bashes out when he nears the bottom of the pillar. Highlight the last lemming with the right-click function, and have him dig facing right one pixel left of the other digger, releasing him and creating a tiny overhang to turn the climber later on. Make the climber dig before the trap, bash near the bottom of the pillar, build across the gap. When the digger on the far left is under the trap, have him bash. When the climber comes back, bash and mine to connect with the other basher; stop this basher with a builder if they aren't perfectly timed to stop each other. Then make the leading lemming bash the wooden slat before the exit.[/highlight]