Leaderboard FAQ

All games from the current week that are reported on the main player reporting page ("/tabs/*") are entered towards the leaderboard. So just use the site for your gamertag (or someone else's) and they will show up if they're in the top 50 for a given board.
This is basically the same thing I did for King's Fall NM and HM and Wrath of the Machine later. I'll show the first 1000 fireteams to finish the raid. As more games are reported on, some teams will get bumped out by other teams that finished first but weren't yet reported on.
All PVP matches are included EXCEPT un-timed events like Trials of Osiris and Elimination. It's relatively rare to see legit kill counts in the top 50 from those game modes and they could be exploited to easily get very high kill counts by a cooperative opponent. (Thanks to the folks at Destiny Trials Report for the heads up about this)
This site simply doesn't have the resources to dump every single bit of game data and sift through it the way Bungie can. Only games from the current week that are already filtering through the site are listed. It's possible, likely even, that some top scores won't get reviewed during the week. When in doubt, Bungie's leaderboard is correct.
For PVP, just after the weekly reset, the site archives a read-only copy of the past week's leaderboard and resets everything. Unfortunately there's no way to go back and add you.