Yep, electrodes, as in the gaming devices. Headsets is the form factor I have in mind, so not necessarily electrodes if this is to be believed. I don't want to commit to burdensome implementation details but voice isn't what I mean - it doesn't count as "unobtrusive" to my way of thinking.

I envision something where I can just form the thought "nearest MacDonalds" (ETA: or somehow bring up a menu selecting that among even a restricted set) without it being conspicuous for an outside observer, and get some form of feedback from the device leading me in the right direction. Visual overlay would work, but so would a physical tug.