Why 'invite contacts' on social media sites

The invite contacts to join on social networking sites does help the social network -- but more important is how much it can help you.  For example, on twitter when I invited my contacts I was surprised to see how many were already on twitter, and I could connect with those people right away.  This made growing my network so much faster, I now have thousands of followers on the various twitter accounts i have...

The same is true on buzzherd... I'm surprised how many businesses bother to make a nice herd on buzzherd, write a couple of blogs, but then forget to import their contact list to get the ball rolling.  Buzzherd is no different than twitter.  You need to spend time in order to get the ball rolling and start seeing some results from social media marketing.