Wolfgang Pichler has released a really cool open-sourced utility library to add a right-click contextual menu to a map developed with the Google Maps API.
The contextual menu includes options to get directions, zoom in or out, center the map and find out 'What's here?'. In fact it mirrors very closely what you get if you right click on a map at maps.google.com.
To add the control to your own maps all you need to do is include the script tag for the source code and add the control with:
For more information, read through the reference and developer's guide.
Via: Google Geo Developers Blog