I don't know what to call this, or how useful it is, but I taught Ruger what I call "Drop-Leash-Stay" yesterday. He's pretty good with it, considering he only learned it yesterday.
We will walk along, and without warning I'll drop the leash to the ground. He's supposed to stop in his tracks and stay while I keep walking ahead. I can walk a block and only when I recall him with "Come!" or slap the side of my leg will he come running to me.
I figure it would be useful if I need to drop the leash and check something out before I bring him into it. We use it for intersections (not busy) in my neighborhood where there's a blind spot that you can only see from the other side after you cross it.
See the video:
Ruger and his new Drop-Leash-Stay command - YouTube