Reveal Admin ID’s
Reveals IDs on admin pages for Pages, Posts, & Categories. Important for many customizations
Maintenance Mode
Adds a splash page to your blog when down for maintenance
All-In-One SEO Pack
Great SEO plugin, makes it easy to edit descriptions
Akismet
A collaborative effort to make comment and trackback spam a non-issue and restore innocence to blogging
Feedburner Feedsmith
This plugin will detect all ways to access your feed and redirect them to your FeedBurner feed so you can track every possible subscriber
Sitemap Generator
This plugin creates a sitemap for your WordPress powered site. Setup to work in conjunction with the Google sitemap generator
Google XML Sitemap Generator
This plugin generates a XML-Sitemap compliant sitemap of your blog
Google Analyticator
This plugin adds the necessary JavaScript code to enable Google Analytics logging on your WordPress blog. Requires Google Analytics account.
WP Database Manager
Allows you to optimize, repair, backup, restore, delete, & backup database. Supports automatic scheduling of backing up and optimizing of database.
Additional information about setting up a new WordPress installation: