These are the Extensions that I use on every Chromium installation that I have. They are mostly all privacy and security related.

Adblock Plus – My preferred advertisement blocking extension. However, I do whitelist websites that I constantly frequent (such as Reddit).

Block Mixed Content – Blocks insecure active content that may attempt to load from within secure pages.

Disconnect – Tries to stop major third parties and search engines from tracking what you are doing.

FlashBlock – Automatically blocks Flash content.

gleeBox – Allows you to navigate through websites and the browser itself via keyboard commands.

KB SSL Enforcer – Automatically redirects you to the secure version of the websites you are visiting (if they exist).

NOREF – Suppresses referrer information on hyperlinks so no one can see what website you came from.

NotScripts – Essentially this is the Chrome answer to "NoScript". It gives you complete control over what runs on a website and increases security by not allowing javascript, plugins, and iframes to run without your permission.

Perspectives – Helps protect against "man-in-the-middle" attacks by checking to see if the certificate a secure web server is sending you is correct. It also looks at what certificates the website has used in the past.

Reddit Enhancement Suite – The absolute must-have extension if you are a Redditor. As the name implies, it adds a number of enhancements that makes your stay even more enjoyable.

Vanilla – A whitelist manager for cookies. It can automatically delete all unwanted cookies in order to help protect your privacy.

YouTube5, Chromed – Forces YouTube videos to play in HTML5.

I hope someone has found at least one of these extensions to be useful. If you have any favorite extensions feel free to list them in the comments section.