Import contacts from different social networking sites and invite to my drupal site
You would use the invite along with the Contact Importer

Invite 


  Invitations are important to create network effects and exponential
  growth of a community of interest. This module provides an Invite a
  friend feature to allow your users to send and track invitations to
  join your site.


Contact Importer


  Contact Importer provides a form for your users to enter their email
  address and password. The contacts from their address book are then
  retrieved.
  
  Contact Importer can be used with any Drupal form. No codding
  necessary. It can be used with an invite module, a user import module,
  an emailing module, or anything else that you can think of.
  
  The current release interfaces with the Octazen or Open Inviter
  retrieval services. But the architecture is modular and can be very
  easily extended to use other retrieval services such as Contact Mines,
  ImproSys, or IpInvite.