jQuery continuous mousedown

Something like

var mouseStillDown = false;

$(document).mousedown(function(event) {
    mouseStillDown = true;
    doSomething();
});

function doSomething() {
    if (!mouseStillDown) { return; } // we could have come back from
                                     // SetInterval and the mouse is no longer down
    // do something

    if (mouseStillDown) { setInterval("doSomething", 100); }
}

$(document).mouseup(function(event) {
    mouseStillDown = false;
});