I particularly like the embeddable slideshow that Ning Photos has, and its companion in Ning Videos, the embeddable player -- so you can put photos or videos on your blog or wherever. Both apps let you e-mail in content from your phone, too. Ning Group has some spiffy HTML parsing and file upload features so you can share documents with folks and incorporate music, pics, or anything else in the forums.
Plus, all three sites have the juicy bits that every site on the Ning platform gets -- things such as cloneability, complete customization, and built-in REST APIs. I've been watching the feeds for clones of photos and videos -- I suppose seeing who's cloned sites you care about is the Web 2.0 version of ego surfing.