A topic that's popped up in a couple of my UNC class discussions: how do you search multimedia and video? Both search for those productions and search within those formats.
It's not nearly as easy as searching for text or photos. Photos can still be tricky finds, because they often rely on users adding comments, tags or other metadata in order to be picked up in search engines. At least with photos, they're often in the vicinity of related text, which helps make things a bit easier to search.
With multimedia, video and even flash productions, Google and other search engines can't always see the content. Here's a link to a short Wired magazine story on who'll become the Google of video: http://www.wired.com/techbiz/media/magazine/15-07/st_videomining/