"# nuke w_hotbox"
You have the option to create buttons that either show up when specific node (combinations) are selected, as well as buttons that will show up no matter what is currently selected.
The hotbox while having a Merge node selected:
For me it changed the way I interact with Nuke completely and it sped up my workflow quite a bit. The ability to move any action to a button that appears near your cursor saves you a trip to the other side of your screen and back pretty often.
Besides that I use it a lot to automate repetitive tasks and actions I would otherwise probably not have taken time for at all. (Think of things that make your script more readable, but don't necessarily contribute to the final image, like (color)labeling nodes.).
However, you can add whatever buttons you like, so it's totally up to you how you put the hotbox to use.