Wordpress plugin | Referal code

im looking for a plugin that we can track a referal code…

Pretty much i want to track all users that subscribe to the website if someone refered them to the site registration. For exampl a promoter will give out a code to the public , and when the site visitor will register and enter the specific code that the specific promoter gave, it will give me a chance to track and know which users registered that was refered by that specifi promoter

what about this plugin, but it doesn’t work with codes though http://codecanyon.net/item/wordpress-affiliate-referral-plugin/5393776

Actually it can be usefull, thanks a lot ill have a look at it

thanks sanvas