As you can see the green little thingy that's below your post count and avatar.
That's your Reputation.
People can increase and decrease other people's Repuation. ( they have to fill in a good reason ).

How to raise it or lower, you press that little white thingy that's between the triangler ! and weird warpish thing.

Yeah that way people that are really usefull.
Get a Rep if the people that were helped are nice enough to give one.

Then you can see which person has a good status ( reputation ).

It's mostly used on GFX forums but it can be used every were = ).
It's not useless.

If people forget to rep that's their bad but there are still people that give rep points to people that are usefull.
So I think it's a perfect system and old exp. Forum users will have more rep then new members.
It's a better indicator then post count =).
Not all the time. I've been on another site for a while but some new members tend to have more rep than me. Probably because they make many accounts just to boost thier rep.
That's why you have to give a reason.
On the forums I have been on there was a special Mod who checked all the Rep Adds en Decreases and check if the reason for them was good.
If not the person who was wrong gets a warning, 2nd time is -5 rep.
ok...i will say:
the reason this is a great idea is beacause you get to know what people think about you.You can also do the same to a person and they will know how you think they are at posting.

Here is a list with all the basic rep lvls.

Anything less then -50: "is infamous around these parts"
-11 to -50: "can only hope to improve"
-1 to -10: "has a little shameless quantity at this point"
0: (default/starting point) is an unknown quantity at this point
10-51: "is on a distinguished road"
50-150: "will become famous soon enough"
151-250: "has a spectacular aura about"
251-350: "is a jewel in the rough"
351-450: "is just really nice"
451-550: "is a glorious beacon of light"
551-650: "is a name known to all"
651-1000: "is a splendid one to behold"
1001-1500: "has much to be proud of"
1501-2000: "has a brilliant future"
2000+: "has a reputation beyond repute"
Yeah but they should start now = D.
But on a gaming forum it's harder to add rep besides somebody answering a question or help solving a problem ^___^.