The Metroid Prime speedrunning community has a combined discord server for all three games due to the massive overlap in the player base.

https://discord.me/metroidprime

Edit: this is no longer the case. See Dyceron's message below.

There is now a new, dedicated server for this game, which can be found here:

https://discord.gg/tjSDqV2Y8s

As of yesterday, Metroid Prime 1, Echoes, Corruption, and soon, Beyond, now share the same Discord server!

Here is the server link:

https://discord.gg/7H7pc5EbKN