Configurable Tag Cloud is a WordPress 2.3 widget that gives you a very nice set of configurable options for your sidebar tag cloud.
Global Post Password enables you to set a global password for all your password-protected posts, and switch password protection on or off from the writing screen with just one click.
Headspace 2 manages meta-data and handles a wide range of SEO tasks, including tagging your posts, creating custom titles and descriptions that improve your page ranking, changing the theme or run disabled plugins on specific pages, and a whole lot more.
Page Category Plus is a WordPress 2.3 plugin that allows for pages to be assigned categories in the same manner as posts.
WordPress 2.3 Related Posts will generate a list of related posts via WordPress 2.3 tags.
Tag Suggest Thing is another tagging plugin for WordPress 2.3 that adds a box to the sidebar that will send a request to the Yahoo! term extraction API to get a collection of (possibly) related terms.
wp-cron Dashboard Display lets you see what cron jobs are scheduled for your WordPress installation.