A lot of people think Lucid Dreaming is meant to be used to do things like flying or having crazy sex, I recently heard a story on Youtube where someone said they had a Mermaid give them a hand job. But this is not what Lucid Dreaming is for. I don't mean to tell anyone what dreaming is "for" or what to do in your own head, I really don't. I just want to let people know about something.
Many cultures believed that the Dream world and the Spirit world were one. Western Medicine started in Ancient Greece with the Asclepeion. These were the first hospitals, and the foundation of Western Medicine, and these people were getting prescriptions for people via dreams.
The Ancient Egyptians also used dreams to talk to the dead. A dead person's "Ba" was said to be able to survive on in other people's dreams. There was recently a book written about this by a Dr. of Egyptology or something like that and she gets way deeper in to this.
http://www.amazon.com/Behind-Closed-Eyes-Nightmares-Ancient-ebook/dp/B00GR2OGEG/ref=sr_1_1?ie=UTF8&qid=1418537468&sr=8-1&keywords=behind+closed+eyes
Here are things that are known by some Native cultures to let multiple people have the same dream.
http://en.wikipedia.org/wiki/Coleus
http://en.wikipedia.org/wiki/Silene_undulata
http://en.wikipedia.org/wiki/Calea_ternifolia
There are TONS more. And there are even Mixtures, like the "Hottentot Tea" which is mainly Imphepo, but also contains a mix of other things.