Basically Id like to see some of the features found in ventrillo, mumble, or teamspeak incorporated into discord to better support squad and unit based gaming.
In other applications voice users can be in multiple voice channels with separate key-binds to control which groups they speak with. This allows squads, platoons, and even company or larger sized units to operate with minimal cross-talk while leaders can be in separate channels coordinating with other units. Furthermore if a leader needs to they could address all channels for faster dissemination of orders.
Another feature of being able to monitor multiple rooms is that a channel can be left open for public visitors to converse while private discussion can happen in another channel without missing important information in either channel such as during some political encounters or even just while hanging out in the main voice channel while keeping an ear to the lobby for visitors.
Finally whispers fill a similar feature while only being a direct connection between players as opposed to an open channel and could potentially be left like mini voicemails. This would be especially helpful with mobile users as text can be tedious.