I'm an ardent fan of Beth's Blog, and have been following along as she's explored the world of widgets.
The widget from her pantheon that I've decided to try out is MyBlogLog. If you look at the dark green rectangle marked "Recent Readers" in the bottom righthand corner of my blog, you'll see my experiment in progress.
If readers of my blog decide to participate, you'll see portraits of recent visitors appearing in the box. Let's think of it as Mash-Ups 101, and see what happens. This could turn out to be a fun way for nonprofit organizations that maintain blogs to build a sense of community.