Visual Event 2 is a bookmarklet, so the install is as simple as dragging a link into the bookmark area of a browser (though it took some hunting to find the link on the Visual Event 2 page - look under the section titled Make It Go).
All of the DOM elements with events attached become color coded, and I could hover over elements for details. In most cases, Visual Event could give me the exact line and file where the event handler lives.
Unlike the Event Listeners tab in Chrome developer tools, Visual Event understands jQuery events (even live events), as well as YUI, MooTools, Prototype, and more.
Great tool, and free!