Mine Trap is a 20man ground fleet action that rewards Romulan Marks and Fleet Marks. Average Romulan Marks per mission is 25. Takes 20mins. Lots of fun and no Borg one shots.
Now if your queuing for this while on New Romulus doing the dailies you should pull in a nice sum of marks. I don't do this everyday, just once every two or three days. That keeps it from getting stale, and free's me up to do doffing/dil dailies/stf's etc.