It is common to write GUI-driven applications which require end users to pass in some variables from the workspace when calling the function to launch the GUI, e.g. myPlottingGUI(X,Y)
UIGETVARIABLES allows your users to interactively select workspace variables from a dialog instead of having to type variable names when launching your app. You can restrict which types of variables are allowed for each input, making it easier for users to successfully pass the right data into your app.

Give it a try and let me know what you think!