What would be the fastest way to get a hold of you?
Of course, it depends on the time of day.
For me, the first thing I would suggest trying is to direct message me on Twitter. I know it seems weird, but if I'm in front of a computer, I probably have Twitter open. If I don't, I still get an email with Twitter direct messages. If I'm not on the computer, I likely still have my cell phone, and I get texts with Twitter direct messages.
If that doesn't work, it probably means I'm at home and the cell phone is in the other room where I can't hear it, so call the home phone.
If I forget my cell phone, the world would be doomed.