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.
Keeps a history of your permalinks no matter what changes you make on your site, and redirects old links to the new ones.
Add RSS Feeds to your template header for Firefox and other browsers to detect automatically. Plugin facilitates adding your comments feed, per-post comment feed and allows for custom RSS feeds to be added. Configure >> Feeds are not excluded to local RSS feeds of your site. Forexample you can add your Twitter or Pownce feed just as easily as adding a comments feed.
A plugin for wordpress which enables AJAX login, user registration and password retrieval.
Using categories as tags in WordPress. This plugin provides a tag cloud and related posts. When using this plugin, you can use the WordPress’ categori …
This plugin allows you to generate a gravatar URL. It also shows LiveJournal userpics in comments.
A inline mp3 player for the web, using javascript soundkit and scriptaculous.