Invite Friends to Groups Just Like Invite Friends Plugin(Not ONly Site Users but External users)

Hi Friends,

If anybody having a plugin to invite outside friends not in our site to Groups so that the created groups will be popular and get more traffic to the Site.

My Requirement is my users will create their village name and invite their friends from gmail,yahoo,facebook and other social network sites just like elgg invitation pluin so that the invited user click the link and register so that he will become member of that group..

Is it Possible to achieve?  Because i need this feature otherwise i need to look into other social network script .But i like elgg verymuch not interested to move to another but no option other than this feature.

Please Help out