function getStickingOutElement(frame, startFrom) {
    var frame = $(frame).width() || $(window).width(),
        startFrom = startFrom || document.body,
        report = [];
    $(startFrom).find("*").andSelf().each(function (i, e) {
        if (parseInt($(e).width()) > frame) {
            report.push(e);
        }
    })
    return report
}
// define who is the frame, and from where to start.
getStickingOutElement(window, document.body)

Ever wondered who is sticking out of a element and creating scroll-bars?

This code checks sticking out elements horizontally, You can quickly change it to see all those elements sticking out on the Y as well by changing "width" to "height".

Open firebug and open console and paste in this function.

When calling the function you can optionally define (by passing arguments) who is the frame, and from where to start to check.

Requires: jQuery on page. (Remember: you can always jQuerify the page and then use it).