I'm getting things buttoned up (pun intended) on a startup we're developing in NYC working a full range of bleeding API's and we've done some heavy surgery on the Youtube API in order to add some pretty cool new UI features. Simply put, we are focused on content creation and curation in a simple, tumblr-esque way.
As we sit now in a closed 'alpha' stage we have a slick new html5 WYSIWG and hopefully we'll be launching with an interesting feature thats inspired by some older, commonly used html tricks using "hotspots" or "Image Mapping". Essentially we wrap up that under-used html trick and make it easy for the user to do on their own, in their browser or device. And without spoiling the fun of the surprise, we'll be using that feature to monetize content for our content creators (and we've also implemented it directly on videos).