Lets see...
/chatconnect - Reconnects you to the chat server if you lose channels/ooc/auction
/flush - Clears your graphics cache - this helps if your map or other windows bug out
/citystatus - Shows the state of the civic levers in your city
/targetauto <partial name> - Cant find that NPC but know he is somewhere near?
/listcommands <category> - lists all the possible commands in a category you specify
/help listcommands - Lists all the categories for the /listcommands feature
/invite <name> - Invites the specified PC to your group
Thats all I can think of without being at my PC... have fun