You must be in the 1.8 snapshots to use this as it contains /execute.
I was playing around with Vechses acid idea he found and I removed the fire effect to see it travel right into the void. I suddenley thought of neutrinos in minecraft but I couldn't get the first part of it (invisible bat) to work so I just watched it destroy a cave underground. Then I came up with the name CaveNoiser as it destroys caves.

What this is, is a few command blocks doing some simple commands first we have the summon command doing /summon XPOrb ~ ~10 ~ {Riding:{id:Bat} (the Y does not have to be 10). The next commands are just removing blocks around the bat as it flies.

Vechses video: http://www.youtube.com/watch?v=mYD-KJJdPgQ&list=UUOy5LOrYA5wVg5F_jAWtwfw

. Its a schematic so you will need MCEdit.

A tutorial for importing and exporting schematics for people who don't know how to use one: http://www.planetminecraft.com/blog/how-to-create-a-schematic-in-mcedit/

. BTW the picture was done with paint and paint is horrible so if you don't like it you can suggest another tool I could use.