Customize Google for IE (CG4IE) is an Internet Explorer extension that enhances Google search results by adding extra information (like links to Yahoo, Ask Jeeves, MSN etc) and giving the user more power over Google interface and security settings.

IFocus is a unique web browsing utility that enables you to clip and monitor the content of your favorite websites. Highly useful if you need up-to-the-minute content, such as stock quotes, breaking news, sports scores and more...

Greasemonkey for IE is an Internet Explorer extension which lets you to add bits of DHTML ("user scripts") to any web page to change its behavior.