As of WordPress version 3.5 (and newer) they have left out the Link Manager link in the admin area. here is a quick recipe to bring it back!

Just paste this code into your functions.php file, and you’re done!

 <?php  	//Activate the Link Manager built in to the WordPress admin 	add_filter( 'pre_option_link_manager_enabled', '__return_true' );  ?> 

Thanks to Tim Berneman for this tip!