Here's an idea to tie in with Museum week.
Usually only about 10 to 20% of a museum/gallery's work is on display at any one time. But imagine if a museum put pictures of all the work it has online. Then allow the public to vote on what should be put on display.
An exhibition for the public curated by the public.
It's far more likely to create discussion about art when the people viewing the exhibition have been part of putting it together.