I have a button that when clicked changes the screen to a world map view, which is really a camera placed high up. My character is too small to see, so I was wondering if I could make a GUI texture that moves with my character using function OnGUI () in Javascript. This would make it so that a marker representing the character would move as the player moves, relative to the worldMap camera.
Take a look at Camera.WorldToScreenPoint().
(Another option would be to attach a large graphic to the player object that's only visible to the 'map' camera.)