Having updated to Tiger on both my Apples here, I have to say that the collection of widgets available is just huge. They can do anything from look up a phone number, monitor web cams, or even post to my blog :). It's the ultimate in organising little tools for various jobs. I currently have 3 clocks for different time zones around the world, the current weather, an app to monitor for available WiFi access, unit converter, Australian Yellow Pages directory, a Wikipedia look up tool, a live camera view of Sydney Harbour bridge, and the widget I'm using to write this post!
I have to say that these widgets are very useful indeed.