I agree with JMD on slow extension support for chrome. If you are looking for extension support, you can always download dev version of chrome. It has preety good extension support already but it still have to come to regular users.
Until extensions are developed for chrome, you can use BookMarklets. (Bookmarklet is a java script code which sits in your bookmark toolbar and when clicked can accomplish mostly same thing as extensions. No dedicated UI components like extensions but it works.)
If you are using GMail for your main email client, you can refer to http://contrapants.org/blog/2005/07/gmailthis.html
Hope this helps.