There are a number of staff jobs which help keep everything going smoothly.
SysOp / Administrator
A SysOp and Administrator are pretty much the same thing; they highest rank available. SysOp's primarily have the job of managing the server itself, channel configurations, role configurations, making things go smoothly on a technical end, though SysOp's can act in a more comprehensive sense if they choose.
Moderator
Moderators are primarily concerned with maintaining the peace on the server and avoiding conflicts between players. Their job is to keep an eye on the role play, make sure the server rules are followed, and that players have respect for each other. This can be a difficult job, so they deserve a huge amount of respect for putting themselves in the direct line of fire for those who don't terribly want to be nice to each other.
Concierge
This less common role acts as a facilitator for role play. These people are focused on making sure people (especially new people) can role play easily. This means playing NPC's or providing information to new players. If you're in need of someone to help with a story, then a Concierge would be the first person to go to for help.