WordPress – The main “engine” behind the website
Akismet – Anyone publishing a WordPress site should use this anti-Comment-Spam plugin
NextGEN Gallery – A well featured gallery plugin
Lightbox 2 – (no longer used on the site – see next item) added into the NextGEN Gallery to give a nice effect when viewing pictures (needs a hack for WP 2.7.x)
Shadowbox JS – a drop-in replacement for Lightbox – no hacks required, and appears to be a nicer effect
AdSense Manager – This plugin helps you to manage your AdSense adverts more easily (rather than pasting code into each page/post/sidebar)
Google XML Sitemaps – Generate’s an XML Sitemap that Google understand – far better than using Notepad!
Collroll – Collapsing Blogroll – allows the links feature in WordPress to be used and displayed in Pages/Posts – once the keyword is in the page/post, you don’t have to keep editing the post to add more links
And the odd hack of php code here and there, where things need fixing, or a plugin doesn’t quite work as expected.