Recently, I've been looking at using zooming interfaces in multitouch, like the much vaunted Seadragon and Google earth. The underlying problem with these sorts of interfaces is that, while direct manipulation of the content is extremely compelling, it's very difficult to index between content that have weak relationships to eachother.
It's easy to get from this:
...but how do users efficiently get from one part of the image map or datacloud to another without a structured hierarchy (zooming is effectively a way to move up and down a tree)?
To get to highly unrelated data over here:
This still strikes me as 1 of the top 3 unsolved interface issues in multitouch (more to come on the other 2). In GUI's this function would typically be handled by a search box or similar command line interface.
Google is a great example of an interface that uses this strategy to move efficiently from one link in a datacloud to another ... but multitouch interfaces are fantastically bad at character input.
How would you go about doing this in multitouch?