Here's the link to Taylor's website with cut-off switches. According to the site, their 4-Post Switch complies with NHRA requirements by having the ability to cut off the battery, alternator magneto etc. I guess if you really want to kill it, and don't mind the extra wiring, this would be the way to go.
For me, I'm good with just cutting the negative side and taking they key with me. I don't stray too far from the car....
