I have to say I've been (pleasantly) surprised by the utility of Dashboard.

While a lot of the widgets coming out are either highly specialized or of questionable (to me) use, there are a number that I either use quite often or which are particularly fun to have.

Out of the stock OS X widgets, I use the following regularly:

• Dictionary/thesaurus
• Weather
• Calendar

In addition, I have these installed (more for fun than for anything else):

iTunesLyrics

Grabs the currently playing iTunes song and gives you the lyrics for it.

http://www.dashboardwidgets.com/showcase/details.php?wid=486

WoW Server Status Widget

This widget lets you check the up/down status of your favorite US, British, French, or German World of Warcraft server from your dashboard

http://www.skia.net/dev.php

There are now a couple of different sites where you can see all of the new widgets that are starting to pop up - Dashboard WIDGETS, and of course Apple's widget site. Personally, since I'll be attending this year's WWDC, I'm going to make it a point to attend the widget-writing sessions and give it a go myself.