Did you know… you can Select Connected Nodes using Tab after selecting a Node in Dynamo?

From Dynamo developer Ian Keough on github:
When a node is selected, try pressing Tab. This will expand your selection by one connection. Pressing Tab again, by two. Etc…
Wish: Select Connected Nodes · Issue #4313 · DynamoDS/Dynamo

Here is a short Screencast of the feature:
Open embedded content: screencast.autodesk.com