Admin Management Xtended: When you want to edit properties of posts/pages, you’ll have to open the edit page, set the new options and save the post/page… which obviously takes time. For those who are using WordPress as a CMS, it’s important to be able to manage contents easily and quickly. That’s what this plugin helps to do.
Colorful Tag Cloud: Designed to render a colorful tag cloud.
Contact Form 7: If you value simplicity and flexibility, Contact Form 7 is a great choice. It allows you to flexibly design the form and mail. You can manage multiple contact forms as well. In addition, it supports many features including AJAX submitting, CAPTCHA, Akismet spam filtering, file uploading, etc.
NextGEN Gallery: An excellent photo Gallery plugin.
Page links To: Make a WordPress page or post link to a URL of your choosing.
Picasa Express x2: Browse, search and select photos from any Picasa Web album and add them to your post/pages.
Shutter Reloaded: An image viewer for your website that works similarly to Lightbox, Thickbox, etc. but is lean and mean at only 10KB size. It does not require any external libraries.
Viper’s Video Quick Tags: Yes, WordPress 2.9 and WordPress 3.0 feature native easy embeds. However this plugin offers more customization than allowed without the plugin (player colors, etc.). It will work fine side by side with the new code and you can opt to use either embed method.
WordPress Database Backup: Creates backups of your core WordPress tables as well as other tables of your choice in the same database.
And one of the ones I like best:
Ozh’ Admin Drop Down Menu: (This one should be built in!) Uses a horizontal menu that gives the admin area more of a “desktop application” feel, and I think it’s superior to a vertical menu. Many neat customizable features.