One of my tenacious ideas is to create a TV-like experience using Web video. In spite of great players such as Boxee, I still feel there's more that can be done.
Secondly, the player should present a simple UI that allows the viewer to surf the enormous amount of existing Web video with minimal interaction. The UI should favour discovery over explicit search. This is not something I've seen often - or at all.
This is why I spent a few nights hacking away at Feedeo (thanks Francis Pilon for the clever name!), an experiment in online video consumption. The main idea is to create channels of continuously running videos, and to provide branch points at each video that the user can explore, then get back to the previous thread he was following. This viewing paradigm is akin to a stack.
This is heavily experimental stuff, so don't expect a beautiful UI - I'm just trying out the interaction model at this stage. Please try Feedeo and I'd love to receive your feedback!