Microsoft has a website dedicated for IE8 where you can download accelerators, web slices, search providers, tools bars and add-ons for IE8 called as Internet Explorer Gallery. You can customize IE8 using the content available in Internet Explorer Gallery. The site also list popular contents like accelerators, web slices and featured contents.
You can use Accelerators to search, map, e-mail, translate, or share content from any web page you’re currently viewing with just one click. Web Slices allow you to subscribe to portions of your favorite websites and, with a single click in the Favorites bar, view and interact with the latest updates you care about most. For example, you can create a web slice of Facebook updates, so that you can get all the updates from your friends without opening Facebook page.
You can also create your own accelerators or extensions and then share it in the gallery.
Get all the top search providers like Live Search, Wikipedia, Yahoo, Amazon, and more to deliver direct results and images that provide you with immediate answers right inside IE8. Browser toolbars and extensions can help personalize the way you use Internet Explorer.