Here's a fun tip courtesy of the "Google Tip of the Day" gadget for iGoogle. The Google Image Labeler
site lets you play a game and help improve Google's image search at the same
time. It's kind of an online version of Pictionary in reverse - you are randomly paired with a partner, both shown the same set
of images, and asked to provide labels for those images. When you and
your partner provide matching labels, you score points, and move on to
the next image. It's a nice brain exercise cum time killer.