Just a line or two of R code can be used to create interactive visualizations. See the featured widgets in the showcase and browse over 50 available widgets in the gallery.
You can easily compose multiple htmlwidgets into a dashboard using the flexdashboard package, which features flexible and easy to specify row and column-based layouts for multiple widgets.
Widgets can be wired together using the crosstalk package. Linked brushing between widgets and client side filtering are currently supported. Use Shiny to create more sophisticated interactions.