I've been digging and landscaping my home for a while, now. I need a big pile of dirt and am therefore digging a dry trench.
It would be cool if somehow it could be used in a defencive capacity - i.e, giving an attack penalty to anyone unfortunate enough to be in or near it, or making it so it has to be filled in before rams can be rolled over it - rather than just sitting there looking pretty. Being able to fill it with spikes or caltrops would be real fun.