I just accepted an invitation from Jagex to become a RuneScape player moderator. This means I can now send priority reports and mute players for serious rule violations. In addition to having a silver crown next to my name when sending messages, I can also post on the official forums as a free user. Besides these things, player moderators don't get any special perks.
For those concerned about us abusing our power, there are guidelines on when we can mute people. I can't disclose much else as the player moderator manual is confidential, but you needn't worry about being muted as long as you follow the rules. :-)
Currently playing: RuneScape