Addon used for EPGP loot system - must have.
Make sure to enable "Remote Addon Management" in CEPGP (it used to be on by default in Classic) - you can do it by using command "/cep options" (or going to Interface -> Addons) and checking boxes like on the screenshot:
Raid management addon - be sure to get it, soon we'll be relying on it heavily.
Used to sync professions recipes among Guild Members.
We recommend disabling "Modify default roster" and "Print info messages" in addon settings: