Squintz, I assume that leaderboards accessible in-game would be calculated real-time, which means more consumption of server capacity and player RAM+bandwidth. A separate website works for me, not that I'm skilled or vain enough to check a leaderboard often.
Has anyone defined what # kills means? Is it kills you participate in, or is it times you provided the final shot? If only the latter, what about a player or ship that does most of the damage (e.g., same as earning boarding rights)?
Another thought about what to put in the leaderboard: how about daily or weekly leaders for each of the items? Daily would have to note a fixed time zone (e.g., GMT) which might disadvantage some parts of the world. Weekly would have less of a fairness issue.