Touchless, here's my opinion: there are no worthless schematics. But in one way you are right: Several schematics are rather there in order to show or to demonstrate a principle while others may easier lead to the building of a working instrument or an add-on.
Let Jason fix these links and I'll think in the meantime how I could perhaps categorize and/or comment these schematics in order to have a "guide" through the selection.