WordPress, for some reason, still asks you to fill in your AIM and Yahoo IM. I don’t know about you but I haven’t logged into Yahoo IM for about 3 years, and AIM since before 2000. User this snippet to change it to the social media you actually use.

/* BEGIN Custom User Contact Info */ 
function extra_contact_info($contactmethods) { 
$contactmethods['facebook'] = 'Facebook'; 
$contactmethods['twitter'] = 'Twitter'; 
$contactmethods['linkedin'] = 'LinkedIn'; 
return $contactmethods; 
add_filter('user_contactmethods', 'extra_contact_info'); 
/* END Custom User Contact Info */ 

Then use this code wherever you want to display it:

<a href="<?php the_author_meta('facebook', $current_author->ID); ?>"></a