There is an option under key bindings to Target Next Exposed Enemy. This hoykey allows people in PvP to very quickly pick out an exposed person in a large group and use an exploit ability on them.
I'd like to see a key binding to Target Next Exposed Friend. This would allow medics like myself to, just as quickly, remove expose effects from a friendly unit. Currently, the quickest way of doing so is looking around and finding them, then targeting them manually.