(Of course if something goes really wrong I might not be able to read this page, but I should be able to get it out of the database, or worst-case scenario, Google’s cache…)

When I have time I’m going to go and rate them all, and maybe even give them some $$$, they deserve it. If you know of any others that are this essential, throw me a comment!

Andrew.

Akismet: Spam blocker. Every WordPress user knows about this one.

CIMY Swift SMTP: I use this to send emails from the site (via a dedicated GMail address) because the normal PHP mail doesn’t seem to work on our server.

Google Analyticator: Automatically adds the necessary JavaScript links to log all your site activity with Google Analytics, which is AWESOME. You can even log outbound links as virtual pages so you can see where people are going when they leave your site.

Google XML Sitemaps: Similar to the above, generates and updates XML sitemaps that all the major search engines understand, and makes it easier to see what’s going on with your site’s indexing via Google Webmaster Tools.

Redirection: This plugin lets you manage Apache mod_redirect settings without messing with Apache config files directly. Dead useful if you want to migrate from one permalink scheme to another without losing your PageRank on the original URLs, for example, because it can redirect from the old locations to the new ones with a 301 Moved Permanently which the search engines respect. (NB This installs its options in the Tools menu rather than Settings.)

SI CAPTCHA: Every site needs captchas these days, unless you don’t allow unregistered comments. This and Akismet between them have done a great job of keeping the site spam-free.

Sociable: Adds the social bookmarking (plus email and print) links that you see at the bottom of this post, much more tastefully and unobtrusively than some other plugins, and supporting dozens of such sites (most of which I hadn’t heard of). I haven’t tested most of them, if you want to, then feel free ;-)

Subscribe to Comments: Gives users the option to get an email when someone replies to a post they’ve commented.

Syntax Highlighter Plus: Supplies the lovely code formatting like you see on this page, and supports a whole bunch of languages.

WP_LinkTools: I use this to automatically post bookmark new posts on Delicious via a dedicated account. To be honest though, I haven’t seen much traffic from there yet.

EDIT: Not just bioinformatics but anything with a life-science perspective.