that can be a modification to the torrent website you are using.. I dont think so there is a software for that, which will sync your torrent folder(s) to your rapidshare or megaupload user account. By doing modification or may be by using available (maybe no one has ever got to this thought) modification to the website (forum) that upload a copy of the torrent file to rapidshare and megaupload when you upload it at their website.
PS: I hope you know the rules of your country about torrents.