I've heard of that before, it called something like C.A.P. or as another naruto site calls it (PAC) System
Credits Awarded for Participation
but the way i've seen it done, is members are graded on the topics for
Length
Creativity
Writing Skill
Length: (1-10 points could be made here)
1-5 points for the number of post made.
1-5 points depending on how long the average post was
Creativity: (1-35 points could be made here)
1-10 how well did the posts relate to the topic?
1-10 how well did the posts react with the others post that were made?
1-15 how interesting ways the topic?
Writing Skill: (1-30 points could be made here)
1-15 Clarity, was each post well written and easy to understand?
1-15 Grammar, did the writer use the correct spelling and/or punctuation marks?
Then the LCWs are added up 1-75 and the member receive C.A.P. point accordingly
C.A.P. is stored some where and every-time the member wants to get a new jutsu, weapon, etc..., they'd use their credits that they have saved up to buy it. That way you give members a reason to stay active and you don't become over run with people begging for jutsus and items that they haven't earned fairly.