Alright, I have to admit I am very intrigued by "shared dreams". Not only does the topic interest me, but I want to find more information on this topic.
So here is a list of shared dream threads which I deem important.

Latest Update: Oct 3, 2018 | 3:01am PST

I've tried it out recently, and some of the experiments I've done... worked. Some, not so much. In a few months, days, weeks, or hours; I will be making a thread about all the information I can collect about shared dreams and shared lucid dreams. Taking a look at the information I have gathered, and the information written by others years ago on DreamViews.

The Man, The Myth, The Legend
You've probably heard of him if you're interested in this thread. Baron Samedi a.k.a. WakingNomad. Probably the one who started it all. His thread on Dream Theory is somewhat related, so it is included. Most of these thread are from him so he should deserve some credit.

The Resources
These resources are listed from my order of importance for reading. Good luck at finding what you need!

These are the important threads you wouldn't want to miss out on!

Shared Lucid Dreaming Tutorial
Description: (Posted by WakingNomad on Sept 25, 2009) This is tutorial by WakingNomad on shared dreams, you need to read this.
Shared Dreaming - How to find other people when lucid!
Description: (Posted by Man of Shred on Mar 01, 2010) The main way to find real people when you are lucid involves changing dreams at will, different people have different methods for this...
Shared Dream Battle Tutorial and Hypothesis
Description: (Posted by WakingNomad on Oct 20, 2015) Energy is essential to dream battles, and understanding it is the key to battle.
Laws of the Dream Plane, Dream Battle Theory
Description: (Posted by WakingNomad on Jul 20, 2010) WakingNomad's theories on the laws of the dream plane, plus extra dream battle goodness!
Shared Dream Etiquette, and Dream Plane Theory
Description: (Posted by WakingNomad on Mar 29, 2010) This is only avaliable to the permission group Deep Dreamers. WakingNomad talks about the true nature of dreams, and the shared dream etiquette.
Less important details, but still interesting!

Shared Dreaming Etiquette part 2.
Description: (Posted by Man of Shred on Sept 16, 2010) How to act in a shared lucid dream - Dreamwalkers vs Nightstalkers

These are extra bonus resources, and resources I wouldn't really know where to categorize.

Welcome To Lucid City
Description: (Posted by WakingNomad on Oct 8, 2015) The purpose of Lucid City is to be a hub for dreamwalkers, those who want to share dreams with others.
Lucid Urth: Shared Dream RPG
Description: (Posted by WakingNomad on Oct 13, 2015) Play a shared dream RPG! However, I highly doubt there will be anyone online.
Video: Travelling on the Dream Plane
Description: (Posted by WakingNomad on Oct 12, 2015) A video by WakingNomad on shared dreams. (apparently this thread has no replies)

More Shared Dreaming Threads to Come!
We got to get more sides to the story right? Let's dive deep!