Yeah, I tried that too with the city I was born in. Oddly enough, though, it turns out that someone already took "NYC.mobi"!

But getting back to reality, I did just register one that should cover all the bases:

YOUAREHERE.MOBI

Not 3 letters, but kind of nice for the domain...I envision an instant self-locator kind of site. Now if only I had access to a satellite...