Add a few different ping options for the map - each with either different sound FX(possibly even vocal) or map ping graphics/colours.
ie:
ATTACK HERE
DEFEND HERE
REGROUP HERE
It allows an easy one click way to communicate with teammates who are not using voice comms(ie pugs)
And secondly - and i cant see this ever happening - allow the ability to draw a line on the minimap that fades after a few seconds - perfect for co-ordinating attack paths etc.