Graphical selection of data views is a fundamental task in interactive statistical graphics. Linked plots provide a form of indirect selection, where direct manipulation of objects displayed in one plot indirectly selects objects in other plots. A pointing device or brush is typically used for direct manipulation, and so this indirect selection is commonly known as linked brushing. Most commonly, linked brushing is applied to two or more scatterplots showing various pairs of variables from a multivariable dataset. This article describes a generalization of linked brushing for the setting where plots display different, though related datasets. With this form of linking, we can graphically explore relationships between datasets. Our linking system is extensible and handles any kind of display of any kind of dataset, as well as arbitrary relationships between those datasets.