Import contacts from the Address Book from Yahoo!, GMail, AOL, Hotmail and other providers. 
The plugin also provides all the nice features of OpenInviter:
<ul>
<li>auto-updates</li>
<li>both local and remote debugging</li>
</ul>
Supported services:
<ul>
<li>AOL</li>
<li>GMail</li>
<li>Windows Live (Hotmail)</li>
<li>Yahoo!</li>
<li>Rediff</li>
<li>Lycos</li>
<li>Mail.com</li>
<li>Mail.ru</li>
<li>Rambler.ru</li>
<li>Twitter</li>
<li>MySpace</li>
<li>Facebook</li>
<li>Hi5</li>
<li>Orkut</li>
<li>GMX.net</li>
<li></li>
</ul>
Services coming soon:
<ul>
<li>GMX.com</li>
<li>Email.it</li>
<li>Fastmail.fm</li>
<li>Canada.com</li>
<li>YouTube</li>
<li>(and many others…) 🙂</li>
</ul>

OpenInviter for WordPress

Allow your visitors to invite their contacts from Yahoo!, GMail, AOL, Hotmail and other providers to your blog.

Simon Wheatley

!!THIS PLUGIN IS BETA, PLEASE LET ME KNOW ANY ISSUES!!
This plugin requires PHP5 (see Other Notes > PHP4 for more).
Allows you to upload a CSV file of names, emails and usernames to invite a lot of people to join your blog.
Plugin initially produced on behalf of <a href="http://www.getambition.com/" rel="nofollow ugc">Ambition</a> a project to help UK Arts Organisations work with IT and digital media.
Is this plugin lacking a feature you want? I’m happy to accept offers of feature sponsorship: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a> and we can discuss your ideas.
Any issues: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a>.
<h3>PHP4</h3>
Many of my plugin now require at least PHP5. I know that WordPress officially supports PHP4, but I don’t. PHP4 is a mess and makes coding a lot less efficient, and when you’re releasing stuff for free these things matter. PHP5 has been out for several years now and is fully production ready, as well as being naturally more secure and performant.
If you’re still running PHP4, I strongly suggest you talk to your hosting company about upgrading your servers. All reputable hosting companies should offer PHP5 as well as PHP4.
Right, that’s it. Grump over. 😉

Invite en Masse

Allows you to upload a CSV file of names, emails and usernames to invite a lot of people to join your blog.

OpenInviter for WordPress vs Invite en Masse