This is a great tip for the User Interface Generator which Iain showed me earlier this week. In the past I have right clicked on a model element and used Visualize > Explore in Browse Diagram to see how it is related to other parts of the user model. That works quite nicely but you don't get a diagram to keep afterwards, which means I often end up using a Freeform Diagram to manually drag on the elements I want to work with.
Instead, right click on a model element in a diagram and choose Filters > Show Related Elements... , on a user task for example. I created a new diagram for the task I was interested in but this is also a good way to extend existing diagrams.
You can just click on OK in the Show Related Elements in Diagram dialog box but there are a few useful options if you use the Details >> button. For example, deselect the Owned Element checkbox from Custom Query [Default] to avoid including task activity diagrams.
You should see the diagram update to include all the parts of the user model relating to your task, which is ideal for making modifications or documenting parts of your model.
You can also increase the number of levels to include, however that can result in some pretty large diagrams!