A "compass" or "radar" mod is a fairly straight forward script, the server sends positions to the client, the client phrases them into the proper range for the gui, and moves the dots on the gui around accordingly. What might be a problem is that up on the radar/compass will always be "north", even if you turn your head, so it could be a bit confusing. But if you want me to go ahead and finish the script and give it to you, tell me, I can.