3 Degrees by Microsoft's NetGen Team connects people into a small group, so you can do fun things together. Throw animations to each others' desktops with winks. Listen together to a shared playlist created from music that you own with musicmix. Chat and send photos instantly. Windows XP Service Pack 1 is required, along with MSN Messenger and broadband Internet.
More info:
hxxp://www.microsoft.com/