I've done this very thing using the Free Nodelet. First, turn on the Free Nodelet under your Nodelet Settings. Then go to your User Settings and enter the following into the Free Nodelet box near the bottom. It results in a link labeled "Toggle Page View" being added to the top of the page near the "print," "w/replies," and "xml" links. Click that link and the sidebar disappears. I usually use it to minimize horizontal scrolling if someone makes a really long line somewhere in a thread. This is based on the code found at this thread.

<script type="text/javascript">
var nodelet_state = 'block';
var lb = "\x5B";
var rb = "\x5D"
function add_toggle_link() {
    var spn = document.createElement('span');
    var rpn = document.createTextNode(' ( ');
    var txt = document.createTextNode( 'Toggle Page View' );
    var lpn = document.createTextNode(' )');

    var lnk  = document.createElement('a');
    lnk.href = "javascript:toggle_nodelets()";
    lnk.appendChild(txt);

    var tbl  = document.getElementById('titlebar-bottom');
    var spns = tbl.getElementsByTagName('span');
    var oldspn;
    var i = 0;
    while (spns.item(i)) {
        if (spns.item(i).getAttribute('class') == "addlinks") {
            oldspn = spns.item(i);
            break;
        }
        i++;
    }

    spn.appendChild(rpn);
    spn.appendChild(lnk);
    spn.appendChild(lpn);
    oldspn.appendChild(spn);
}
function toggle_nodelets() {
    nodelet_state = (nodelet_state != 'none') ? 'none' : 'block';
    var elements = document.getElementsByTagName('table');
    var elnum;
    var content_width = (nodelet_state == 'none') ? '100%' : '80%';
    document.getElementById('monkbar').style.display = nodelet_state;
    var tds = document.getElementsByTagName('td');
    for (tnum = 0; tnum < tds.length; tnum++) {
        var td = eval("tds" + lb + "tnum" + rb);
        if (td.className == 'main_content') {
            td.style.width = content_width;
            break;
        }
    }
    for (elnum = 0; elnum < elements.length; elnum++) {
        var el = eval("elements" + lb + "elnum" + rb);
        if (el.className == 'nodelet_container') {
            el.style.display = nodelet_state;
            break;
        }
    }
}
add_toggle_link();
</script>
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