IP Visitor Tracking

Is there an HTML or Javascript code that will log the Ip's of visitor's to a website? If so, what is the code.

server side. either CGI (like perl) or ASP or PHP. HTML and javascript are client side browser interpreted.

In PHP the value gets sucked into:
$REMOTE_ADDR;

and that is a part of the built in $_SERVER variables with php....
here is a list:
http://www.phpfreaks.com/phpmanual/page/reserved.variables.html

if your paying for hosting, normally you get access to something that keeps track of it, you can probably get to it from your control panel... should you have one.