from Mashable.com. Here are some examples.
AjaxWP – Adds AJAX to all aspects of your WordPress site speeding up the load times.
Alexa Rank – Display your Alexa rank with pride.
Ajax Comment Preview – Allows readers to preview their comment before submitting.
asTunes – Retrieves data from your Audioscrobbler/last.fm profile and posts it as a list on your blog.
Codebox – Side scrolling box for displaying code snippets.
Crossroads – Adds thumbnails and comments from your Flickr account.
FireStats – Full featured statistics including referrers and popular pages.