I'd like to make it like I've seen some companies do with affiliates and such when a person comes from "sitea" to my site, if that person buys a hosting plan I will know they came from "sitea". I have looked at hotscripts but I am just not sure what is the best way to do about this.... Anyone done this, what did you do?

if you have a hit counter like whatcounter on your page you can see where all your refferals come from

http://www.whatcounter.com/

You can also use extreme tracking: http://www.extremetracking.com