Cow catchers. The triangular thing at the front of a train. Not so much 'catchers' as 'exploders', though.
Madness string 99426
The reality is I kinda like the rock. I don't see the need for a piece of hardware or a program when the rock works fine. There is something to be said for simplicity and I don't think its gonna get any simpler than a rock. It's basically an on/off switch.