Most of these commands are the basic need-too-know things for a Minecraft User.
/m <playername> <message>: Allows you to speak to a specific person, and only they will see it.
/r <message>: Will reply to the last player to send you a private message.
These are used when either reporting grief, asking to buy Spawners, Warps etc.
/pe open <message>
Example: /pe open I would like a grief check here. - Make sure you type this standing at the point that was griefed.
/pe list - Lists all of your open petitions
/pe close <number>
/pe view <number> - Do this is you want to read any comments from staff or if petition if it's closed.
These commands allow you to teleport to certain locations.
/sethome <homename>: Sets the target of the /home command where you are standing. (maximum of 2).
/delhome <homename>: Removes a previously set home.
/home: Lists your homes that have been set.
/home <homename>: teleports you to the home you set.