Microsoft SearchTogether IE7 plugin enables collaborative searching
Why exactly would anyone want to use this service? Say you're planning a vacation and you're looking up air fare, hotels, tourist destinations, and restaurants where you might want to eat. As you search, you can save your history and share it with other members of your family who you'll be traveling with. You can also see the searches they've conducted and let them know what you think of the results. Of course, this is just an example. You can also work on group projects, plan a dinner menu, or look for birthday presents for your dad.
You need a Windows Live ID to run SearchTogether. But Microsoft doesn't require you to use Windows Live Search as your search engine. You can use Google, Yahoo! or Live Search, or select multiple search engines.