Google+

We all know that it's big, so we'd like to be part of it and try it out.

Sadly, they were not accepting new registration due to capacity in trial period.  But now, they opened the registration channel again for those who received invitation previously, so catch the time and be part of it!

http://www.google.com/+

I've just in :)

Charles

Update: Google has just brought the "Invite" button back!  You can now invite as many people as possible!