I love the plugin! The caching feature is awesome--definitely keeps the API query load low.
Quick question: how hard would it be to add a feature where you could save images forever to the media/uploads folder? That would be amazing. Instagrate (a pretty cool plugin, incidentally) has that feature.
I'm thinking about adding an extension to the plugin for an image-approval process (for decency/relevance sake). Images will default to "display:none" until approved in the backend. Once approved, the "display:none" will be removed by script, allowing image to display (until approval is modified).