NPCs as geographical indicators

Maps are great when designed well, but landmarks also help.

While roaming alleys in Deus Ex, I realized that I was using particular NPCs like landmarks to tell me which direction to go.

I was able to do so because the NPCs were various and unique. One had wild red-dyed hair. Another had a green mohawk.

If your NPCs are going to be just standing around anyway, why not make them useful in this way?