Google Toolbar has a useful feature called AutoLink which detects the content from a page that follows some predefined patterns and adds links to pages that offer more information. AutoLink detects US addresses, UPS tracking numbers, International Standard Book Numbers (ISBN) and Vehicle Identification Numbers (VIN) and links to relevant pages from sites like Google Maps, Amazon or CarFax. Despite its name, AutoLink adds the links only after you click on the Google Toolbar button and also shows the links in a drop-down menu.
The latest version of the Google Toolbar for IE (Google Toolbar 5) adds two new patterns: email addresses and URLs. If you click on AutoLink, Google Toolbar will transform into links all the email addresses and the web addresses from a page. You can click on the button again to highlight the content that has been detected, but a better idea is to see all the results in a drop-down.
In 2005, when AutoLink became a part of Google Toolbar 3, many people complained that Google changes the content of web pages, but they ignored that users need to click on a button to add the links. It's also worthwhile to mention that you can change the services that are linked using this feature and that Google doesn't make money from referrals.