Who's that guy near you?
Problem: I want to know who's near me and I want to be able to talk to them in isolation to the rest of the marine team.
Suggestion: Show on my HUD the names of marines in the same zone as me. Could order by distance, maybe only show up to 3 marines. Have a second push-to-talk button that broadcasts only to those marines. Show on the HUD when somebody is talking locally.