I just found out about a free tool called Twiveaway that helps you get more Twitter subscribers by automating Twitter Giveaways. You can check it out here: http://www.twiveaway.com/ (no, I'm not an affiliate) I haven't used the tool yet, so if you use it feel free to post what you think of it here.
Sounds great, thanks for posting... unfortunately is closed right now Does anybody have any more info about this service, ie, does it work as promised, etc?