They can all pretty much be reduced to a skin on top of an abstract syntax tree, since that's all they really are.

Circuit-based skins work well in the right context. Do a Google Image search for "unreal blueprints" to see many examples of them in use. Blueprints visual scripting probably powers the high-level logic in a video game you or someone you know has enjoyed.

The other popular approach is fill-in-the-blanks, a visualization that looks more like a tree than a graph. The first good version of this I saw was the Warcraft 3 scripting system. It inspired the visual scripting system we built for Tribes, SWAT, and the first Bioshock back in the day.

You can also follow Eve for some modern experiments along these lines: https://github.com/witheve/Eve