I positively love widgets. I have the Random Books from My Library widget on my LibrarysCat Book List Blog. On my personal blog I have a postcrossing widget and a wonderfully fun Wordle. If you have never done one before, you should visit my blog and try it! It makes a word mosaic of sorts with the most common words from your blog.
I was fortunate to participate in a library program called 23 Things. We had to blog about it and while I no longer update it, there are some fun things linked there...photo mosaics, sandboxes, wikis, technorati, delicious, bubblr, and of all things::::LibraryThing! It is rather funny looking back at my first experience there! We basically learned about Web 2.0 applications and had to work with them from our own offices...it was great. Thanks to the PLAN folks for providing me with this opportunity.
Great question as always.