In a previous post I showed my Canon wide angle conversion lens for my G9. Yes, it's an awkward thing but, given that I have the G9, can be useful both indoors and outdoors. The picture below is the widest angle view of a small bedroom that can be captured with the normal G9 lens (35mme).
The next view is with the camera (tripod mounted) in the exact same position but with the wide angle converter attached to yield a 26mm equivalent lens.
At first, the increased angle of view is not so impressive; however, it is significant. Note that the 26mme of the G9+converter is slightly wider than the 28mme of the G10/G11.