Akismet
http://codex.wordpress.org/Plugins/Akismet
Akismet comes standard with WordPress, and it’s absolutely necessary. A high-traffic blog will generate a vast amount of spam, and this drops it to a trickle. All WordPress installations should use this!
All in One SEO Pack
http://wordpress.org/extend/plugins/all-in-one-seo-pack/
This excellent plugin handles the primary tasks related to optimization of your pages for the search engines. Titles, keywords, etc. Very comprehensive.
Auto Thickbox
http://wordpress.org/extend/plugins/auto-thickbox/
I am personally a fan of Highslide for displaying images and galleries, but this is very low overhead: Thickbox is already built into WordPress, and this enables support transparently when you insert images into posts and pages. Hard to argue with the ease!
CMS Tree Page View
http://wordpress.org/extend/plugins/cms-tree-page-view/
If you use a lot of pages in your site, then this plugin is really handy. It provides a collapsible outline view of the pages in your site. You can expand and contract any branch of the outline by clicking, and can open the editor for any page at will.
Contact Form 7
http://wordpress.org/extend/plugins/contact-form-7/
Easy to use and versatile plugin for creating contact forms. It’s easy to have as many forms as you want. Plugins exist that enhance CF7 to save the results in the database instead of emailing the results. Very elegant because of the ease of use.
Google Analyticator
http://wordpress.org/extend/plugins/google-analyticator/
Simple to use: plug in your Analytics ID, and you’re ready to go. You can tell it where to place the code (head or foot), or just use the defaults.
Google XML Sitemaps
http://wordpress.org/extend/plugins/google-sitemap-generator/
Generates an XML sitemap of your site every time you make a change, and publishes the change to the major search engines. Lots to tweak, but it works pretty much right out of the box.
Post Snippets
http://wordpress.org/extend/plugins/post-snippets/
I’m relatively new to this plugin, but it opens up some great possibilities. Basically, you define named fields along with the HTML code for using them. When composing a post or page, you can ask to insert any of your predefined snippets. After choosing one, it will prompt you for the named fields, and then insert the modified HTML text into your post. This table of plugins was created using a pre-defined box layout, with Post Snippets to prompt for specific fields. It seems like a nice way to reduce formatting errors when typing new stuff into a page, especially for non-technical people using the WordPress backend. The WYSIWYG editor gets confused occasionally, and non-techies occasionally whip the underlying HTML into a frenzy—this may provide an easy way to maintain the formatting.
TinyMCE Advanced
http://wordpress.org/extend/plugins/tinymce-advanced/
Extends the TinyMCE editor in a lot of ways, making the thing usable. The best enhancement is a dropdown menu for classes defined in your theme, allowing you to style spans of text.
WP-Ads
http://thesandbox.wordpress.com/wpads/
A simple plugin for putting ads in your site. The neat thing is that it drops custom code into your pages wherever you want, whether containing ads or other code. You can set up multiple ads to rotate in the same place, of course. It also tracks impressions (but not clicks). This basically gives you a shortcode that can drop an arbitrary unit of code into the given location.
WP-DBManager
http://wordpress.org/extend/plugins/wp-dbmanager/
Absolutely necessary to have this. It lets you schedule backups for archiving or emailing, schedules optimizing the MySQL database, and lets you run limited SQL queries.
WP Simple Paypal Donation
http://www.tipsandtricks-hq.com/wordpress-paypal-donation-plugin-942
I’ve used this simple interface to making donations to an organization using PayPal. You can see this in action at www.kelleyhousemuseum.org.
WP Simple Paypal Shopping Cart
http://wordpress.org/extend/plugins/wordpress-simple-paypal-shopping-cart/
I’ve used this simple interface to the PayPal shopping cart in several places. You can see this in action at www.kelleyhousemuseum.org.

I read some welcome news today about the Search for Extra-Terrestrial Life (SETI) project. They have started pointing a radio telescope in West Virginia at a list of stellar systems that are likely to have planets within habitable parameters (between 0 and 100 degrees Celsius). They have 1235 planets on the list, identified by the Kepler space telescope, and they will gather 24 hours of data on each planet. The Green Bank telescope can gather 300 times the amount of information as the radio telescope at Arecibo, so the data will be pouring in!
Here’s where you come in. SETI uses the BOINC distributed computing infrastructure to process data using volunteer computers. All you have to do is install the BOINC screensaver, and tell it which project you want to join. There are many teams around the world—your team gets part of the credit for discovery if your computers discover the first verifiable signal from an alien intelligence.
Join my team! We are called AstroScum, Team 747680. Even though we are only 3 strong now, our combined scores for data processing are better than 76% of the teams out there. But I suspect that there are some guys out there with access to server farms that are running the screensaver. The links to locate and sign up are in the right sidebar—please join!