Other site widgets

suncat posted about a LibraryThing widget, and I know there are Last.fm, Twitter and Delicious widgets that people can add to their blogs, etc. I've been thinking about doing S2 modules for them all, where all someone has to do to configure them is provide their username (and password if necessary, etc), if they want to enable them for their journal; can anyone think of other services/sites/etc that would be interesting to have?