Google Chrome Extensions : Must have Chrome Browser extensions
The most important feature released in Google Chrome 4 is the support for extensions.
To install an extension, visit Google Chrome's extension gallery and pick one of the more then 1000 extensions that are currently available.
Here are some of the most useful extensions that add missing features to Google Chrome:
Google Dictionary shows the definition of a word when you double-click on it. It only support monolingual dictionaries and a small number of languages.
Email this page. Firefox's contextual menu has an option called "send link" that lets you send a link to the current page using your favorite mail client. This extension has a similar functionality, but it only lets you pick the default mail client and Gmail.
RSS Subscription Extension. This extension shows an orange icon in the Omnibox when it detects feeds and lets you subscribe to one of the feeds using your favorite feed reader. You can select one of the popular feed reader that are available by default (Google Reader, iGoogle, Bloglines and My Yahoo) or you can add another feed reader.
Docs PDF/PowerPoint Viewer - a simple extension that detects the links to PDF, PPT and TIFF files and opens the files in Google Docs, so you can view them without installing additional software.
Slideshow - a great way to view the images from sites like Flickr, Picasa Web Albums, Facebook, and Google Images in a slideshow.
Empty New Tab Page - a simple extension that replaces Chrome's new tab page with a blank page.
Secure Login Helper redirects you to the HTTPS login pages for sites like Twitter, Facebook and Twitter.
FlashBlock disables Flash content for all web pages and replaces it with a placeholder.
(src: http://googlesystem.blogspot.com/2010/01/10-must-have-google-chrome-extensions.html )
