Calendar Cloud displays yearly calendars containing 12 months weighed by their post counts.
fGallery Categories Widget allows you to show a link to the different galleries you made with the fGallery plugin.
Limit Posts Automatically lets you automatically choose when to cut your post excerpts on the front page.
WP-Members restricts WordPress content to be viewable by registered site members.
wp-richcomments lets your blog subscribers attach flickr photos and YouTube videos to their comments.
User Level Themes allows a site administrator to select different themes for users with and without administrative access rights.