One subject that is currently interesting me is real-time sharing of documents over a network. Imagine being able to to work with someone on the same programming or writing project, even if you are thousands of miles apart. I regularly use Instant Messenger's “Request Assistance“ option to help my mother back in Ireland with her computer, but sharing a document seems to introduce an entirely new way of working.
One of the most interesting related projects I’ve read of is called “FaceTop”, which combines a shared desktop with video-conferencing (another of my favourite things). Check out this article, the screenshots tell the story. WiReD also have a nice piece on it. The current version is running on Mac OS X, but don't let that put you off - they mention a Longhorn version. If you happen to have a Mac, check out SubEthaEdit which does a similar thing, albeit without the video conferencing aspect.
On Windows, the latest Service Pack for OneNote – a brilliant application that has changed the way I do work – allows sharing documents. It’s great being able to scribble notes in real time, and knowing your collaborator is seeing exactly the same thing. I hope this feature is built into Word at some point.