Setting a cookie value

[hd65]

Here's what I have..
An image(1001.jpg)displayed in a frame.
And a button to set a cookie.

Here's what I'm trying to do...
When the button is clicked I want the cookie name set to whatever(the name I can change later if I need to) and here is the hard part I need the value set to the image name(1001.jpg). This is easy enough if I set the value within the script but I can't do to the number of possible images.(200++)
I can use something like this to get colse but it's not realy there.
setCookie("1001", parent.imageside.location.href);

Any ideas at all would be great
thanks
paul