Magic Gallery is a complete gallery solution for WordPress.
MembersBlog allows you to lock down your blog to members only.
Video Thumbnails makes it simple to display video thumbnails from embedded videos in your templates.
All in One SEO Pack automatically optimizes your WordPress blog for Search Engines.
Fast Secure Contact Form lets your visitors send you a quick E-mail message and blocks all common spammer tactics.
Theme-Check allows you to run checks on the current theme before uploading to WordPress. This plugin uses the same API and is kept more or less in sync with the WordPress.org uploader tool.
wpStoreCart is a full featured e-commerce platform built atop of WordPress.