Social Bookmarking and Tagging
Amazon.com lets you search user tags to find books and other products sold through this popular online shopping site.
Delicious lets you save and tag interesting links on the web.
Docstoc combines file sharing and social networking. Members upload documents they agree to share. Documents are categorized broadly as legal, business, financial, technology, educational or creative. Other members also may tag or comment on the documents.
You may browse, display and e-mail documents without becoming a member. However, to upload and share, tag, comment on, or download documents, you must register with the site.
This search engine crawls and indexes information about people. According to documentation at the site, it seeks out Web page bios, social network profiles, blog entries and more. It further allows members to add tags, pictures or web links, or vote on existing information to increase the relevancy of the information it provides.
Search by name, e-mail address or tag. You may also limit results by location, gender or approximate age.