This little mod:
http://www.fallout3nexus.com/downloads/file.php?id=22
has made my game amazing.
No longer do I know if that person on the horizon is a friend or foe. Do I shoot first? Do I wait in case it is a friendly face?
No longer when an enemy runs away can I radar-track him or know exactly where to go. Combined with Arwen's mod it is now common for NPCs to hide around corners and ambush me as I pass.
No longer, in the dark and dank underworld of the subways and sewers, is the darkness a minimal problem b/c my trusty compass immediately hones in and alerts me anyways....
This mod has made the game sooooo much more suspenseful and fun.
I highly recommend it to people who want a grittier more realistic wasteland experience.
One additional note: this mod simply puts in a new menu file - so it is permanent. Back up your menu folder in the Fallout3 Data if you decide you don't like it and want to go back to the vanilla