User will have many links. He can choose any of them. Every link will contain different parameter value.
No need for selecting. "SELECT" tag represents the combo box.
But that doesn't jive with your first post. You said that you want the link to pass a parameter from the select. What if the select hasn't been used yet?
Also, is the select just for this one link? Again it's easier to submit a form than to build URLs on-the-fly in JavaScript. So you want to go that route if at all possible.