WebSchemas/socialAccount2

http://schema.org would be a property, expecting a URL as value and defined by the types http://schema.org/Person and http://schema.org/Organization to capture their social accounts

Markup example

<div itemscope itemtype="http://schema.org/Person">
 <link itemprop="socialAccount" href="https://plus.google.com/109412257237333861202?rel=author"/>
 <link itemprop="socialAccount" href="http://www.twitter.com/johndoe"/>
 ...
</div>