[Denied]Friend Tracker
This could be an expansion of the "nearby players" option. You would have the option to set it to "Nearby Friends"
When you open up the map, people on your friend's list could show up as icons of a different color or matching their sprites, so you could fly and walk over to them.
Could also be implemented for Teams, but would probably be overwhelming and clutter up the map.
It would be cute seeing like the character heads on the map where they are currently located (if on the same channel as them), but now that the friend list has been expanded so much, it could look very very cluttered on the map with all the current location icons.
For this reason I think Greck's suggestion is better.
Even then, it's laregly unecessary. Can just send a 'where u at?' and knowing where everyone is at all times could get stalker-y.