Facetious lets you add a faceted – often called an ‘advanced’ – search form to your website.
WP Snippets makes it very easy to reuse fragments of content (i.e. Snippets).
Facebook makes your site deeply social by integrating functionality from Facebook.
Nav Menu Images enables uploading of images for nav menu items on the menu edit screen.
OSM displays maps in your WordPress blog using the OpenLayers technology.
W3 Total Cache allows you to improve site performance and user experience via caching.