Links for groups to make it easier to join/leave them as needed.

Intended for:
Groups that offer services but little in the way of conversation/interesting content.
Groups that are "spammy" that I want to see in smaller doses.
Groups that generate excessive "feed."

Proofreaders, Editors, and learning.

OEE
The Proofreader Group
Looking For Editors
Proofreading, prereading, and editing
Editors R Us
School For New Writers
Several other useful links on their main page.

The Writers Group

Promotion and Art

The Shameless Self-Promotion Bureau
Art for Fanfiction
Twilight's Library
Everyone is an Admin
I just want a comment
PP-SPA
Alphapinkie Reviews
Canterlot's Finest
Blunt Review Group
Best Stories Ever
Cadance's Library
Celestia's Library
Completed Story Compendium
502 Fiction
Authors Helping Authors
Author Support
Blunt reviews
Criticism Central
Rage Reviews
Seattles Angels
The Pleasant Commentator and Review Group
My Groups

Coco Pommel
Sonata Dusk
Zippoorwhill
TwiFlank
F.U.C.K.
Jake Rules
The Shippingverse Reserved
Tagging Reserved
Tagging Help
Other Tag

Misc. Tools, Blogs, etc.

Emote Extender

B.A.T.S.

Content Control: "Busy" Groups that I have limited interest in.

Anime Crossovers Group
The Princesses
The Lunaverse
Youngverse
ijab group
Cheating is Magic
Cheese Pie
Children of Equestria

Content Control: "Character Based" groups.

Pairings:
TwiDash
TwiLuna
Twilight's Marem
Twilestia is the Bestia
AppleDashLight

Celestia and Luna Fiction

Cheerilee's Class

ScootaBelle
DiamondBloom

Individuals:
Twilight Sparkle
Alicorn Twilight
Twilight is Best Pony

Rainbow Dash
Alicorn Rainbow

Alicorn Fluttershy

Luna is the Best Pony
Protect Celestia
Nightmare Moon is the Best Pony

Scootaloo
Sweetie Belle is the Best Pony

Silver Spoon

The GREAT and POWERFUL TRIXIE
Sparkler

Applejack is worst pony