Your early Christmas present from EclipseSource: a custom-widget that displays, controls and reacts to a Google-Map. While there have been similar widgets before, this one is the first (as far as I know) that runs in RAP and RCP without any changes.
The widget is currently hosted at github, so feel free to check it out, use it in your application or fork it to add your improvements. Also check out Holger Staudachers carousel widget for RAP to see another example.
“Traditional” custom widgets for RAP are by no means obsolete with this, as they still have certain advantages (slightly better performance, themeability, can use rap client components). But for the cases mentioned above, the browser widget can make your life much easier!