Bookmarked How To Make The Most Of Trello By Syncing Cards Across Multiple Boards by an author (blog.trello.com)

The Unito Power-Up operates under the assumption that no Trello board should be an island. Collaboration works better when it crosses the boundaries of boards, and even tools. That’s why Unito is a great way to sync (connect) information between Trello boards, letting your cards exist in more than one place at the same time.

I really like the look of this power-up to sync cards across different boards. It addresses one of my biggest frustrations with Trello.