As an Search Engine geek, I like to keep my eye on what the "big dogs" are doing. Wikipedia has to be one of the biggest dogs in the search engine game. It's hard to do any search and not find a Wikipedia web page on the first page of results.
I think they are on to something with having image landing pages with relivent data. While this wouldn't be something of value to most users on most website, it maybe extermely useful as a way to increase indexing of pages that utilize these resources. Landing pages could be created for all types of media resources with descriptions, meta data and other SEO considerations. This would surely help in the indexing of images, videos and pdf documents. The media focused landing pages could be contained within a separate XML site map and have longer term indexing request information.
My only concern with this type of approach, is my gut tells me that Google only likes to index the top pages from a website that match the overall relevance of the websites content. So it might be a better idea to "cherry pick" media that accents the content. This could include graphs, related pdf documents and product photos.
I might have to revisit this concept at another time. There are too many items on my to-do list to worry about this experiment at this time.