I use http://www.put.io for this and highly recommend it. If someone has already downloaded the tracker you are trying to get you get it instantly, so for anything even vaguely popular you are able to get it (or after the first person downloads the file the rest are just pulling directly from S3). They also have great customer service, ios and chromecast apps etc.
Someone has a swank Mac menubar app for Putio that's a browser helper; any magnet or regular torrent file gets added to your put.io queue simply by clicking the link within your browser.
