Wouldn't it be cool if you always had a self-categorizing directory of the links you find in Google? A "Digg This" link beside every link you get in a Google search! It's really a shame that Yahoo! bought up Del.icio.us because it could have been very well integrated into the Google fabric. But, as we all know, Google doesn't seem to enjoy buying up cool Web technologies, only cool 3rd party apps (Picasa, Sketchup, Keyhole).
But just imagine if this Google cache program were more readily viewable from anywhere online, without the need to isntall an external browser application. You'd never lose that cool Google finds again.