Advanced Tagline – Installed this one for fun and flexibility.

Akismet – A must have… blog spam is annoying and frequent.

All in One SEO Pack – Meta tags, etc… if you don’t know what this does – research it.  It will be worth your time.

Best Posts Summary – Awesome plugin.  Gives daily, weekly, or monthly post summaries.

CyStat – Awesome stats plugin for wordpress. Tab right in the admin menu.

Digg This Reloaded – Adds the Digg button to the bottom of single posts.

FeedBurner FeedSmith – Some people don’t like to redirect feeds via feedburner.  It was worked well for me to this point, so still use the functionality.

Google XML Sitemaps – Great plugin, auto-generates a sitemap for google robots.

RSS Footer – Nice plugin that lets you tweak the footer of individual posts in your RSS feed.

Secure and Accessible PHP Contact Form – Great and easy to impliment contact form for wordpress.

SimpleTags – Adds technorati tags to the bottom of posts.

Social Homes widget – A widget for the sidebar that allows you to link to your various social networking websites.

Spam Karma 2 – This plugin worked well for a number of years.  It has been discontinued and Akismet has been doing the trick.  So will probably be pulling it soon.

Subscribe To Comments – As the title sounds, allow your readers to subscribe to idividual comment feeds.

Tweet This – Adds the twitter button to the bottom of blog posts.

TwitterCounter – Displays the number of followers you have on Twitter.  A fun little addition.

WordPress Automatic Upgrade – Awesome must have plugin.  As the name implies, automatically upgrades your wordpress installation every time a new version comes out.

WP-Amazon – Generates amazon links with your affiliate id to add into posts.

So that is actually quite a few plugins.  Hopefully that will give you some ideas on how to geek out your own wordpress install.