I like the new "Annotations" feature on YouTube. Opens up interesting possibilities for contexualizing video content in interesting ways, from adding speech bubbles to highlighting certain parts of the shot for the viewer. Now anyone can create a popup music video!
Here's my first experiment with using annotations, using a video of me getting body scanned at Eyebeam Studios a few months ago. Super simple and publishes nearly instantly. Gotta love the interwebs.