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.
Marekkis Watermark plugin for Wordpress
A plugin to creating floating contact form on home, pages or posts.
Plugin developed for inserting the sitemap link to footer without any hassle.
This is a plugin creating a new tweet including a URL of new post on your wordpress.
An animated banner, news ticker, for Posts, RSS feeds or Images.
This plugin adds link for the category feeds after post content.
Global Setting allows you to add, update and delete the global variables for your blog. Get Paid version at : http://just4u.x10.bz/global
This plugin changes the file permissions of thumbnails, pictures and files after the upload.
Import posts, comments, tags, and attachments from a Posterous.com blog.
Site Sensor is a website uptime monitoring service with WordPress specific checks.