See All of the Weather Widget's Weather Modes
The Weather widget in OS X's Dashboard (in OS X 10.4 and later) displays a six-day forecast along with the current weather--complete with a large graphic representing the current conditions. As I check the Beaverton, Oregon weather this morning, for example, I see a large glowing sun, and a forecast high of 90F. Different weather conditions offer different graphics, so over time, you'll see a number of different images appear.
But what if you live somewhere where the weather rarely changes--Phoenix, for instance. Or what if you're just curious about the various different weather graphics available? Here's an oldie-but-goodie tip to let you see them all with just a couple of keypresses. Open Dashboard (F12), then open the Weather widget if it's not already visible (click the Plus sign, then click the Weather widget on the row of available widgets).
You'll also notice that the town turns to Nowhere, and the forecast features round-number temperatures and minimal weather variety. Keep clicking until you've cycled through all the available graphics--and keep an eye out for the one animated graphic. (And yes, this trick still works in Snow Leopard.)
When you're done looking at all the pretty pictures, your Weather widget will still be stuck in Nowhereville, but that's easily fixed--just press Command-R to reload the Weather widget, and things will return to normal.