Some Wordpress plugins are often updated, which is good think. Plugins that are updated are 100% compatible with last Wordpress version and they also are the most secure possible. A plugin that has not been updated for a long time might not work with last Wordpress version and might create a security breach for you website.
A live post filtering plugin. Choose which categories to show in the filter and watch the post show/hide without reloading.
Add a contact form to any post, page or text widget. Messages will be sent to any email address you choose. As seen on wordpress.com with added i18n.
This is a plugin originally authored by Steve Smith. It detects all ways to access your original WordPress feeds and redirects them to your FeedBurner …
Custom Post Archives creates a fully featured set of archives for each post type using a robust back-end and native templating functionality.
Custom Page Menus plugin allows custom menus to be defined on a per-page basis.
Give you the ability to upload files that you have in your Media Library. It also let you insert more then one file into a post at a time.
The Change User plugin allows the administrators of a blog to log in as any user of the blog.