With BfA just around the corner and the thought of raiding etc again once they open up, the Communities tab might have come at just the right time.
Subbie has been a busy Tauren and put together a list of Raiding/Mythic + Communities for you to join which can be found here. There are a multitude of other types of Communities that are available you can find them in the megathread or in the forum list.
They come as Faction specific or B.Net ones for both factions to join. So you can decide if you want to associate with the opposition or not.
A great idea for those wanting to casually raid and the like without having to flit around a load of guilds trying to find the right one for you. All with the bonus that if you’re not able to find a community for what you want, you can make one! without needing to leave your guild!
Don’t forget to check out the support centre for it either!