The three groups in question are below, along with descriptions of each and my thoughts. Hopefully this post can help people find the right group "home" for them and also have a better understanding of the dynamics of each of these internet cultures. (Not that you can link directly to each group via the image.)
Discussions can involve intricate details and often it moves beyond the concept of a generic Viking costume to trying to place a garment into a specific time and place in the Viking world. Weave structures are discussed, proper dyes and mordants for the period, appropriate use of imported goods and other wonderful, detailed topics that invite others to share their experiences and research and to expand what they already know by listening to others.
If you are new to Viking Clothing, I recommend highly that you just spend some time browsing the posts and files here. This group can be a very inspiring site and it is full of great advice. And please understand that if you post your work, you will get feedback. It may not be the praise you would get on another forum, but if you keep in mind that this group is dedicated to the pursuit of authenticity you can learn a great deal from its members and really start taking your garb to the next level.
The official group message is below:
One final note: Remember to respect others and have fun.