I'm using the Image Rotator Widget within the Responsive theme.
However I had to add extra CSS to make the widget responsive - so sharing for others to use and maybe to be adopted into the plugin.
Need to add:
#widgets .widget_dk-image-rotator-widget .irw-widget {
max-width: 100% !important;
}
#widgets .widget_dk-image-rotator-widget img {
max-width: 100% !important;
}
http://wordpress.org/extend/plugins/dk-new-medias-image-rotator-widget/