Read the full article at mashable.com.

Some of the modules require a fee but usually the fee is reasonable for the functionality added.

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.

Google PageRank - Allows you to display your Google Page rank on your blog.

Hardened-Trackback - Generates a single use trackback to help fight trackback spam.

imgViewJX - Refreshes an image on your main page from a selected directory.

Live Spell Checker - Adds a spell checker to the admin area to check your posts with.

Plug ‘n’ Play Google Map - Adds any post you make with longitude and latitude to a Google Map on a separate page.