Found an interesting page about
fisheye views, applied to XUL menus. If you’ve seen the OS X dock,
you’ll know what a fisheye view is, but you may not have thought about the
cunning metrics going on behind the scenes to make it feel natural. Exscade
uses distance measurement only (as shown in the diagram), but there’s a
short paragraph covering velocity sensitive approaches. I couldn’t get the
demo to work… Bummer.

Fisheye views are a way of getting more Fitt’s Law bang-for-your-buck, by
artificially creating larger areas to aim at. They’re especially useful for
cramped or small interfaces – but I’m stretching my head to figure out how
to apply this to PDA interfaces. There’s no such thing as a hovering cursor
on a PDA, you see.

Sadly, I know Mark
would have enjoyed sinking his teeth into these problems.