At the time of writing, I have these plugins installed...

• All in One SEO Pack
  Out-of-the-box SEO for your Wordpress blog.
• Dagon Design Sitemap Generator
  Generates a fully customizable oldfashioned sitemap. Google loves sitemaps (have a look at the bottom of this site where it says "sitemap")
• Easy Contact
  An easy contact form you can use to set up a contact page (have a look at my contact page)
• Link Cloaking Plugin
  Excellent plugin to cloak outgoing links in your posts, pages, sidebar, etc... (see my woothemes goto-links in the sidebar)
• WassUp
  Excellent plugin to analyze your visitors traffic in real time with stats, charts and a lot of chronological informations.
• WordPress Database Backup
  Cheap hosting providers usually don't backup things for you, so here's your chance to have a backup feature for free.
• WP Super Cache
  A traffic surge might come to your site one day. Be prepared. Here's a very fast caching module for WordPress, ideal to handle heavy traffic. (You can activate this plugin in "off mode", and switch it on and off again whenever you need it)

Oh, BTW, I missed the Thank a Plugin Developer Day some days ago... Mister Matt Mullenweg declared Jan 28th as the official "Thank a Plugin Developer" day. Hope this post makes it up. Thanks everybody!