is_human() is the simplest yet most extensive human verification system available on the WordPress market. Users can choose one of three verification types, or have the script show one at random on each page-load.
WP Comment Remix allows you to reply and quote links for commentators and also provides a full upgrade to the edit comments pages in the admin panel.
WP Help is a plugin that allows you to create a simple help or instructional page in the WordPress Admin that will display customized information of your choosing.
Fixes the media uploader HTTP Error that some WordPress (2.5+) configurations suffer from.
Photo Galleria is a simple, yet elegant, plugin for photographers, designers and WordPress 2.5 users alike who want to beautify their WordPress photo galleries using the jquery framework.
WP Movie Ratings is a wordpress plugin that makes rating movies very easy. At its core is a bookmarklet, which combined with Internet Movie Database (imdb.com) and a little bit of AJAX magic lets you rate movies with just 1 click.
Widgetized Admin Dashboard is a WordPress Plugin for 2.5+ that lets you edit the WordPress Dashboard in the Design > Widgets area.