Razesdark

This plugin will allow all authors to have their own tweets shown on in the widget area of their posts, by adding it to their profiles. 
That way any multi-author blog can let their bloggers promote their own twitter account and not a joint account.

Author Based Twitter Widget

A Author based twitter widget, made to help multi author blogs have individual twitter widgets for their authors.

Nimrod Flores

GooglePlus Multi-Authorship provides a straightforward solution to properly add Google+ Authorship markup to the head of each post and page on a multi-authored site.
It follows the recommended use of the rel=”author” link tag to point to a Google+ profile as described in <a href="http://googlewebmastercentral.blogspot.com/2013/08/relauthor-frequently-asked-advanced.html" rel="nofollow ugc">this FAQ</a> on Google’s official webmaster blog.
<ul>
<li>It adds only the rel=”publisher” link tag on the home page, front page and archive pages</li>
<li>It adds both the rel=”author” and rel=”publisher” on single posts and pages.</li>
<li>The appropriate author’s Google+ profile is used for each single post and page.</li>
<li>You can set a default Google+ profile to be used as a fallback if there’s no Google+ profile specified for an author in his WP user profile settings.</li>
</ul>
For questions and support, please post them at the <a href="http://nimrodflores.com/googleplus-multi-authorship" rel="nofollow ugc">plugin page</a>. I can’t provide quick help if you post your questions in the forum as I am not always in the forums.

GooglePlus Multi-Authorship

GPMA provides a straightforward solution to properly add Google+ Authorship markup to the head of each post and page on a multi-authored site.

Author Based Twitter Widget vs GooglePlus Multi-Authorship