I've found little use for Dashboard. I use the stock and weather widgets and that's about it. Package Tracker is a extremely handy widget for tracking packages. It works well as a widget since it's something I simply want to check out once or twice a day. It also supports Growl, so if I'm sitting at my computer I get a instant notification of the status. The interface is well thought out and it's free, as far as I can tell.

The 4.0 beta is out with a lot of improvements. check it out at Mike Piontek's website.