There is a better way for this. But cost one extra account.

But I have 2 accounts because I use two at the same time all time.
Just make one character in the other side faction, and use software called keyclone (cost $10 or so) and everything you type in WoW1 will be typed in WoW2.

So /who *whatever-name* and you'll get info about where that guy is.

Good against stealthers that just ganked you or something.

Not an exploit but still useful if you do have 2 accounts anyway.

Expensive if you get another account for only this.

I usally run some /who (opposite big city) to see if there is any hostile in my town I'm in, if there is I ask them for invite and know exactly where they are if they accept and I go there with my other lvl 70 and gank them. :P