Once every three months would be my input.....

Sounds a good idea to me.

Once in a month, two or three, heck i dont care, but its a great idea.

And what would be the reward? well a grand prize of 50 points or so and also we can have a runner up prize. may be the winner can also be given a premium membership free of cost.

top ideas here

i think every month to be honest. it's still rare isn't it

and good idea about the prize too. i think you're right, you should get about 50 rank points or something

and each "match" you play best of three, just like normal tournaments, and if you win you get 3 points, just like the world cup... i'd love to see it done

It would be quite time consuming. Marathon tourney is nearest you'll get. What you thinking is more like a league which is on upcoming features: v1.65 - offical league - 2005 Q4
- Fixture scheduling and auto league running

it's nothing like the league... do you even know how the world cup works?