Leaders. /ginfo - Gives basic information about your guild
g
o
ginvite
gremove
gpromote
gdemote
gmotd
gquit - Removes you from your guild
groster - Gives an entire guild roster (officers and leaders only)
gleader
gdisband - Disbands your guild (guild leader only) Otherwise the guild rank is just a status symbol. You can check your guild rank by opening up your character name. Your rank is listed under your name.
Guild Tips
Use your guild to help each other through the game. Use a guild to find party members and help each other do quests.
Loan each other money for items.
Pool trade skill components for specific people in the guild. This will allow them to get to a higher skill level much sooner.
Share information for players that are stuck or confused.