Trim Usernames trims the usernames to eliminate accidentally entered ( usually during copy/paste) spaces, tabs, colons, and double quotation marks.
Better Comments Manager is an extension of the default WordPress comments manager. It allows you to reply to comments without visiting the post page and view comments based on post.
Impress displays blog stats showing the number of users, posts, pages, comments, categories, words, and more on your blog.
If You Liked That follows the content of a post with links to a user selectable number of other posts in the same category as the main post.
Classic Posts will allow you to select posts from the post manager to be stickied and then randomly displayed.
Clean Trunks provides SEO Friendly URLs for post and page slugs automatically.
And, Planet RSS & XML Ajax Feed Checker checks as many feeds as you want, and for each one gives a small report that will help you, at a glance, determining if the feed is still there and still fresh. (not a plugin)