There is lots of research on zoomable user interfaces. A variation is detail-in-context interfaces where the points of interest are magnified while the rest is compressed. The OS X icon bar is a good example. Check out http://pages.cpsc.ucalgary.ca/~sheelagh/wiki/pmwiki.php?n=Ma... (contains many references to ZUI research as well) It's been suggested to use a trackball with your left hand to zoom in and out while keeping the mouse in your right hand (vice versa for left-handed people). I'd like to see that happen.