We took exactly what you said under "9. Photo/video sharing services" and put our own spin on photo/slideshow sharing. Presentation is key to us. We wanted people to be able to build clean, but custom, slideshows. Make a slideshow's presentation appeal to the users emotions on level apart from the photos themselves. We've still got a long way to go, but the response has been overwhelmingly positive so far.

http://www.photatobug.com if anyone's interested. :)