Fingernails on a chalkboard has never bothered me. Neither does rubbing a balloon. I wonder what the criteria for having or not having the negative physical reaction they describe is.
That would be E(D) = -2y[sub i](a-a[sub 0])e^(-D/D[sub 0])
I'd be a little wary about putting my head in that thing...maybe it would be more helpful if it too had a display with a smiley face on it.
http://www.opendns.com/ Pretty simple DNS service, which I've used for a while.