Honestly cowmeat,

If you are interested in such algorithms, I would advise you to apply them making real money in real life, I do.

But if you want an active community of gamers, it will have to relate to activity.
If Toribash Ranks or Clan Ranks reflected the best players and didn't include teamwork and activity levels, you might as well have about 10 members who fight it out to see who is is #1 and who is #10.
Game Over!

BTW, I would quickly move on to something else.
I can win Portal single player and Mirror's Edge and I can play Minecraft or Terraria or Mass Effect or whatever and win all day everyday.

This is a team effort and in that case, activity rules.

That's just my opinion.