I’ve seen countless times websites that would allow me to dig through my GMail, Hotmail, Yahoo, contact list to invite friends over. A pretty neat piece of code that can help a website to grow its userbase quite well.
Open Inviter is the open source bit of code that can allow users to install this functionality wherever needed. The list of supported communities and CMS platforms is huge! Open Inviter can link to users to their contacts in GMail, AOL, Yahoo!, MySpace, Orkut, Twitter, Facebook, Plaxo, LinkedIn, and loads more.
Having this integrated with any “Invite a Friend” function on a website is essential. Written on php 5, it runs on Apache so should be easy to install and integrate.
Have a look at their demo. I’ll have to give a try to their installation process soon!