Went to a workshop where the speaker was talking about this:
THE RAINBOW BRIDGE (Spiritual Concept)
The Rainbow Bridge bridges the mundane to the spiritual, connects the physical you and the spiritual you aka your soul. Once you can get into contact with your spiritual self you will begin to know your true self, your true desires, your true purpose in this life. There was much more to it than that but this is what I took from the lecture. As soon as I heard this I thought an actual Rainbow Bridge (not the one in Niagara Falls either

) would make an interesting Meeting Place 1. because it's potentially a spiritual goal, 2. there are lots of associations to rainbows, Oz, magical creatures, treasures, etc, 3. we have a rainbow in the MM logo.
Could be interesting for us to find a rainbow bridge, cross it and see what awesomeness awaits us at the other end.