Keeping URL Variables

Hello, Is there a way to keep a URL variable every page you go to without editing the <a> tag's href attribute everytime? Basically, I have skin options and depending on what the URL variable "skinid" is, it shows that skin (I have multiple websites all using this PHP script). What I want to be able to do is get the value of skinid, then if the user goes to another page via a link or form, that skinid is still chosen. What's happening right now is if a user clicks a link, the skinid in the URL is nolonger set so it defaults to the default skin. Is there a way to always pass the variable to any part of the side through a global include without having to put it in the URL in the <a> tag every time? Thanks, Stephen Craton http://www.melchior.us