The following are a few add-ons that every guild member is recommended to have.
This will be used to schedule instance runs and raids. Download
This is a very helpful add-on for questing. It puts quest objectives on the worldmap for easy finding. Download
A simple add-on that puts coordinates into the worldmap and the minimap. When searching WoWHead or Thottbot and the comments list coordinates, now you know where to go! Download