We have a brand new tool!
It was suggested here in G2G by Regis Giampersa.
This tool will show you the people in your Watchlist who are not connected to the global family tree, i.e. their relationships, even through marriage, do not connect them in any way to the vast majority of other people on WikiTree.
About 3/4 of the people on WikiTree can be connected to each other within 100 degrees of separation. (Our Connection Finder counts and displays the connections using three "anchor" people, currently Kevin Bacon, AJ Jacobs, and JK Rowling.)
About 1/4 of the people on WikiTree are unconnected. Most of them have very small family trees. Just a little genealogy TLC might be able to connect them.
Who is on your Watchlist and needs connecting? One click will show you.
Onward and upward, for the single family tree,
P.S. If you have questions, spot any bugs, or have suggestions for future improvements to this tool, post them here. Some early beta testers reported seeing a couple random people who aren't on their Watchlist, or aren't unconnected. On the latter, note that it takes 24 hours to update connection status.