We actually used to have a reputation system, around 2005? It stopped working with the latest vBulletin update at that time, so I don't know how it would work with the current vBulletin system; we have a lot of custom-made stuff that sometimes refuses to work with upgrades.
I think it was good at that time, since we had username changes associated with points, as well as getting points from a gaming arcade we had on the forum. Now, however, we have ATRL+, so there's no real reason to have the reputation system. It doesn't really seem like it'd add anything now.