Ok, this list originated on the Scootaloo group, then got posted to the Cutie Mark Crusaders group. And the Apple Bloom group, the Babs Seed group, plus the Sweetie Belle group. And since arcum42 asked, you get a copy of it here, too.

First off, Scootaloo's group seems pretty popular. Though ponies always seem to be writing her as orphaned and homeless for some reason.

Next, Apple Bloom. She founded the crusaders, leads us, rebuilt the clubhouse, and is generally a good friend. So why does her group only have 936 members, including me and arcum42? Why don't you go over and join the Apple Bloom group? (Disclaimer: I'm now one of the admins. I am for the Scootaloo group, too.)

And Babs Seed, who runs our Manhattan branch, has her own group, too!

And there is a Sweetie Belle group, too. I don't know why...

And there are also a few other Scootaloo groups:

Clueless Filly runs the Scootabelle Empire, which appears to be about me and Scoots. Though she seems to have gone missing at some point, just like the admins for the Sweetie Belle group and the Cutie Mark Crusaders groups. Edit: I'm now the admin for the Sweetie Belle group!

There's a Scootalove is Best Love group. It's about Scootaloo and Rainbow Dash.

And there's a Scootaloo: Achievement of Flight group for fanfics about Scootaloo learning to fly.

Just for fun, I created a Sweetie Belle: Achievement of Magic group to go along with the last one, though there isn't much in it yet. Maybe a dozen fanfics, and a pretty good discussion on magic.

If anypony has other groups that are related to any of the Crusaders, you can add them to this thread...

Scootabuse is Best Abuse is a nearly empty, inactive group for Scootaloo abuse. But the members there have been active in other groups, so if things are posted, they'd probably respond.

Scootafamily is a group focusing mostly on stories where Scootaloo has a loving family from the start of the story. It was just started, so it's fairly small, but it probably belongs in the list.