Drop it in functions.php, call it with the social network desired, and echo it in an href tag.

custom-social-links.php

function get_sharing_link($network) {
	if($network) {
		switch($network) {
		
			case 'facebook':
				return 'http://www.facebook.com/sharer/sharer.php?u='.get_the_permalink().'&title='.urlencode(get_the_title());
				break;
			
			case 'twitter':
				return 'http://twitter.com/intent/tweet?status='.urlencode(get_the_title()).'+'.get_the_permalink();
				break;
				
			case 'linkedin':
				return 'http://www.linkedin.com/shareArticle?mini=true&url='.get_the_permalink().'&title='.urlencode(get_the_title()).'&source='.get_site_url();
				break;
			
			default:
				return false;	
		}
	}
	else {
		return 'Must pass $network variable to function';
	}
}