The global constants, specifically the user-defined ones (within the Workflow configuration) are a great tool for making quick changes. I would love to be able to include the value of these constants directly within a comment: the Comment tool, the captions for Tool & Control Containers, or the Annotation of individual tools. My immediate use-case would be to clearly show what the constants are set to, directly on the canvas, though there are certainly a lot of other uses as well.