Cuil, a new search engine that wants to compete with Google to include results that Google omits. The interface and the way results are displayed is beautiful, however, the searches are poor.
Xobni (inbox spelt reverse) is a new plug-in for Outlook that makes your experience faster and more efficient. It turns your mail-client to a social network, readily displaying your most frequent contacts, conversations, fast search, analytics and files (attachments).
Still in beta (4249), the application requires .NET Framework 2.0 installed on your system.